Enzymes having alpha amylase activity and methods of use thereof

ABSTRACT

The invention relates to alpha amylases and to polynucleotides encoding the alpha amylases. In addition methods of designing new alpha amylases and methods of use thereof are also provided. The alpha amylases have increased activity and stability at increased pH and temperature.

RELATED APPLICATION DATA

This application claims priority of U.S. Provisional Application No.60/270,495, filed Feb. 21, 2001, now pending; U.S. ProvisionalApplication No. 60/270,496, filed Feb. 21, 2001, now pending; and U.S.Provisional Application No. 60/291,122, filed May 14, 2001, now pending,all of which are herein incorporated by reference in their entirety.

FIELD OF THE INVENTION

This invention relates generally to enzymes, polynucleotides encodingthe enzymes, the use of such polynucleotides and polypeptides, and morespecifically to enzymes having alpha amylase activity.

BACKGROUND

Starch is a complex carbohydrate often found in the human diet. Thestructure of starch is glucose polymers linked by α-1,4 and α-1,6glucosidic bonds. Amylase is an enzyme that catalyzes the hydrolysis ofstarches into sugars. Amylases hydrolyze internal α-1,4-glucosidiclinkages in starch, largely at random, to produce smaller molecularweight malto-dextrins. The breakdown of starch is important in thedigestive system and commercially. Amylases are of considerablecommercial value, being used in the initial stages (liquefaction) ofstarch processing; in wet corn milling; in alcohol production; ascleaning agents in detergent matrices; in the textile industry forstarch desizing; in baking applications; in the beverage industry; inoilfields in drilling processes; in inking of recycled paper; and inanimal feed. Amylases are also useful in textile desizing, brewingprocesses, starch modification in the paper and pulp industry and otherprocesses described in the art.

Amylases are produced by a wide variety of microorganisms includingBacillus and Aspergillus, with most commercial amylases being producedfrom bacterial sources such as Bacillus licheniformis, Bacillusamyloliquefaciens, Bacillus subtilis, or Bacillus stearothermophilus. Inrecent years, the enzymes in commercial use have been those fromBacillus licheniformis because of their heat stability and performance,at least at neutral and mildly alkaline pHs.

In general, starch to fructose processing consists of four steps:liquefaction of granular starch, saccharification of the liquefiedstarch into dextrose, purification, and isomerization to fructose. Theobject of a starch liquefaction process is to convert a concentratedsuspension of starch polymer granules into a solution of soluble shorterchain length dextrins of low viscosity. This step is essential forconvenient handling with standard equipment and for efficient conversionto glucose or other sugars. To liquefy granular starch, it is necessaryto gelatinize the granules by raising the temperature of the granularstarch to over about 72° C. The heating process instantaneously disruptsthe insoluble starch granules to produce a water soluble starchsolution. The solubilized starch solution is then liquefied by amylase.A starch granule is composed of: 69-74% amylopectin, 26-31% amylose,11-14% water, 0.2-0.4% protein, 0.5-0.9% lipid, 0.05-0.1% ash,0.02-0.03% phosphorus, 0.1% pentosan. Approximately 70% of a granule isamorphous and 30% is crystalline.

A common enzymatic liquefaction process involves adjusting the pH of agranular starch slurry to between 6.0 and 6.5, the pH optimum ofalpha-amylase derived from Bacillus licheniformis, with the addition ofcalcium hydroxide, sodium hydroxide or sodium carbonate. The addition ofcalcium hydroxide has the advantage of also providing calcium ions whichare known to stabilize the alpha-amylase against inactivation. Uponaddition of alpha-amylase, the suspension is pumped through a steam jetto instantaneously raise the temperature to between 80 degree-115degrees C. The starch is immediately gelatinized and, due to thepresence of alpha-amylase, depolymerized through random hydrolysis of a(1-4) glycosidic bonds by alpha-amylase to a fluid mass which is easilypumped.

In a second variation to the liquefaction process, alpha-amylase isadded to the starch suspension, the suspension is held at a temperatureof 80-100 degrees C. to partially hydrolyze the starch granules, and thepartially hydrolyzed starch suspension is pumped through a jet attemperatures in excess of about 105 degrees C. to thoroughly gelatinizeany remaining granular structure. After cooling the gelatinized starch,a second addition of alpha-amylase can be made to further hydrolyze thestarch.

A third variation of this process is called the dry milling process. Indry milling, whole grain is ground and combined with water. The germ isoptionally removed by flotation separation or equivalent techniques. Theresulting mixture, which contains starch, fiber, protein and othercomponents of the grain, is liquefied using alpha amylase. The generalpractice in the art is to undertake enzymatic liquefaction at a lowertemperature when using the dry milling process. Generally, lowtemperature liquefaction is believed to be less efficient than hightemperature liquefaction in converting starch to soluble dextrins.

Typically, after gelatinization the starch solution is held at anelevated temperature in the presence of alpha-amylase until a DE of10-20 is achieved, usually a period of 1-3 hours. Dextrose equivalent(DE) is the industry standard for measuring the concentration of totalreducing sugars, calculated as D-glucose on a dry weight basis.Unhydrolyzed granular starch has a DE of virtually zero, whereas the DEof D-glucose is defined as 100.

Corn wet milling is a process which produces corn oil, gluten meal,gluten feed and starch. Often, alkaline-amylase is used in theliquefaction of starch and glucoamylase is used in saccharification,producing glucose. Corn, a kernel of which consists of a outer seed coat(fiber), starch, a combination of starch and glucose and the inner germ,is subjected to a four step process, which results in the production ofstarch. The corn is steeped, de-germed, de-fibered, and finally thegluten is separated. In the steeping process, the solubles are takenout. The product remaining after removal of the solubles is de-germed,resulting in production of corn oil and production of an oil cake, whichis added to the solubles from the steeping step. The remaining productis de-fibered and the fiber solids are added to the oil cake/solublesmixture. This mixture of fiber solids, oil cake and solubles forms agluten feed. After de-fibering, the remaining product is subjected togluten separation. This separation results in a gluten meal and starch.The starch is then subjected to liquefaction and saccharification toproduce glucose.

Staling of baked products (such as bread) has been recognized as aproblem which becomes more serious as more time lies between the momentof preparation of the bread product and the moment of consumption. Theterm staling is used to describe changes undesirable to the consumer inthe properties of the bread product after leaving the oven, such as anincrease of the firmness of the crumb, a decrease of the elasticity ofthe crumb, and changes in the crust, which becomes tough and leathery.The firmness of the bread crumb increases further during storage up to alevel, which is considered as negative. The increase in crumb firmness,which is considered as the most important aspect of staling, isrecognized by the consumer a long time before the bread product hasotherwise become unsuitable for consumption.

The preparation of syrup process contains proportions of polymers withdegrees of polymerisation (DP) greater than or equal to 4, which couldbe troublesome. U.S. Pat. No. 5,141,859 proposed a process for thepreparation of a syrup with a high maltose content employing twosuccessive saccharification steps. This document advocates, in fact, aprocess comprising a first saccharification step in the presence of abeta amylase and a subsequent saccharification step in the presence of amaltogenic alpha amylase. According to this document, the maltogenicalpha amylase is used after the first saccharification step with betaamylase to hydrolyse the oligosaccharides (from DP3 to DP7) andessentially the maltotriose (trisaccharide) to maltose and glucose.

There is therefore a need in the industry for the identification andoptimization of acid amylases, useful for commercial cornstarchliquefaction processes. These second generation acid amylases will offerimproved manufacturing and/or performance characteristics over theindustry standard enzymes.

The publications discussed herein are provided solely for theirdisclosure prior to the filing date of the present application. Nothingherein is to be construed as an admission that the invention is notentitled to antedate such disclosure by virtue of prior invention.

SUMMARY OF THE INVENTION

The invention provides an isolated nucleic acid having a sequence as setforth in SEQ ID NO:1 and variants thereof having at least 50% sequenceidentity to SEQ ID NO:1 and encoding polypeptides having alpha amylaseactivity.

One aspect of the invention is an isolated nucleic acid having asequence as set forth in SEQ ID NO:1, sequences substantially identicalthereto, and sequences complementary thereto.

Another aspect of the invention is an isolated nucleic acid including atleast 10 consecutive bases of a sequence as set forth in SEQ ID NO:1nucleic acid sequences, sequences substantially identical thereto, andthe sequences complementary thereto.

In yet another aspect, the invention provides an isolated nucleic acidencoding a polypeptide having a sequence as set forth in SEQ ID NO.: 2and variants thereof encoding a polypeptide having alpha amylaseactivity and having at least 50% sequence identity to such sequences.

Another aspect of the invention is an isolated nucleic acid encoding apolypeptide or a functional fragment thereof having a sequence as setforth in SEQ ID NO:2 and sequences substantially identical thereto.

Another aspect of the invention is an isolated nucleic acid encoding apolypeptide having at least 10 consecutive amino acids of a sequence asset forth in SEQ ID NO:2 amino acid sequences, and sequencessubstantially identical thereto.

In yet another aspect, the invention provides a purified polypeptidehaving a sequence as set forth in SEQ ID NO:2 amino acid sequences, andsequences substantially identical thereto.

Another aspect of the invention is an isolated or purified antibody thatspecifically binds to a polypeptide having a sequence as set forth inSEQ ID NO:2 amino acid sequences, and sequences substantially identicalthereto.

Another aspect of the invention is an isolated or purified antibody orbinding fragment thereof, which specifically binds to a polypeptidehaving at least 10 consecutive amino acids of one of the polypeptides ofSEQ ID NO:2 amino acid sequences, and sequences substantially identicalthereto.

Another aspect of the invention is a method of making a polypeptidehaving a sequence as set forth in SEQ ID NO:2 amino acid sequences, andsequences substantially identical thereto. The method includesintroducing a nucleic acid encoding the polypeptide into a host cell,wherein the nucleic acid is operably linked to a promoter, and culturingthe host cell under conditions that allow expression of the nucleicacid.

Another aspect of the invention is a method of making a polypeptidehaving at least 10 amino acids of a sequence as set forth in SEQ ID NO:2amino acid sequences, and sequences substantially identical thereto. Themethod includes introducing a nucleic acid encoding the polypeptide intoa host cell, wherein the nucleic acid is operably linked to a promoter,and culturing the host cell under conditions that allow expression ofthe nucleic acid, thereby producing the polypeptide.

Another aspect of the invention is a method of generating a variantincluding obtaining a nucleic acid having a sequence as set forth in SEQID NO:1 nucleic acid sequences, sequences substantially identicalthereto, sequences complementary to the sequences of SEQ ID NO:1 nucleicacid sequences, fragments comprising at least 30 consecutive nucleotidesof the foregoing sequences, and changing one or more nucleotides in thesequence to another nucleotide, deleting one or more nucleotides in thesequence, or adding one or more nucleotides to the sequence.

Another aspect of the invention is a computer readable medium havingstored thereon a sequence as set forth in SEQ ID NO:1 nucleic acidsequences, and sequences substantially identical thereto, or apolypeptide sequence as set forth in SEQ ID NO:2 amino acid sequences,and sequences substantially identical thereto.

Another aspect of the invention is a computer system including aprocessor and a data storage device wherein the data storage device hasstored thereon a sequence as set forth in SEQ ID NO:1 nucleic acidsequences, and sequences substantially identical thereto, or apolypeptide having a sequence as set forth in SEQ ID NO:2 amino acidsequences, and sequences substantially identical thereto.

Another aspect of the invention is a method for comparing a firstsequence to a reference sequence wherein the first sequence is a nucleicacid having a sequence as set forth in SEQ ID NO:1 nucleic acidsequences, and sequences substantially identical thereto, or apolypeptide code of SEQ ID NO:2 amino acid sequences, and sequencessubstantially identical thereto. The method includes reading the firstsequence and the reference sequence through use of a computer programwhich compares sequences; and determining differences between the firstsequence and the reference sequence with the computer program.

Another aspect of the invention is a method for identifying a feature ina sequence as set forth in SEQ ID NO:1 nucleic acid sequences, andsequences substantially identical thereto, or a polypeptide having asequence as set forth in SEQ ID NO:2 amino acid sequences, and sequencessubstantially identical thereto, including reading the sequence throughthe use of a computer program which identifies features in sequences;and identifying features in the sequence with the computer program.

Another aspect of the invention is an assay for identifying fragments orvariants of SEQ ID NO:2 amino acid sequences, and sequencessubstantially identical thereto, which retain the enzymatic function ofthe polypeptides of SEQ ID NO:2 amino acid sequences, and sequencessubstantially identical thereto. The assay includes contacting thepolypeptide of SEQ ID NO:2 amino acid sequences, sequences substantiallyidentical thereto, or polypeptide fragment or variant with a substratemolecule under conditions which allow the polypeptide fragment orvariant to function, and detecting either a decrease in the level ofsubstrate or an increase in the level of the specific reaction productof the reaction between the polypeptide and substrate therebyidentifying a fragment or variant of such sequences.

The invention also provides a process for preparing a dough or a bakedproduct prepared from the dough which comprises adding an amylase of theinvention to the dough in an amount which is effective to retard thestaling of the bread. The invention also provides a dough comprisingsaid amylase and a premix comprising flour together with said amylase.Finally, the invention provides an enzymatic baking additive, whichcontains said amylase.

The use of the amylase in accordance with the present invention providesan improved anti-staling effect as measured by, e.g. less crumb firming,retained crumb elasticity, improved slice-ability (e.g. fewer crumbs,non-gummy crumb), improved palatability or flavor.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are illustrative of embodiments of the inventionand are not meant to limit the scope of the invention as encompassed bythe claims.

FIG. 1 is a block diagram of a computer system.

FIG. 2 is a flow diagram illustrating one embodiment of a process forcomparing a new nucleotide or protein sequence with a database ofsequences in order to determine the homology levels between the newsequence and the sequences in the database.

FIG. 3 is a flow diagram illustrating one embodiment of a process in acomputer for determining whether two sequences are homologous.

FIG. 4 is a flow diagram illustrating one embodiment of an identifierprocess 300 for detecting the presence of a feature in a sequence.

FIG. 5 illustrates a sample Standard Curve of the assay of Example 2.

FIGS. 6 a and 6 b show the molecular weight fragments in syrups usingenzymes of the invention and commercial enzymes.

FIG. 7 is the sequences of the invention.

FIG. 8 shows a comparison of oligosaccharide profiles for SEQ ID No: 2and commercial amylases.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to alpha amylases and polynucleotidesencoding them. As used herein, the term “alpha amylase” encompassesenzymes having alpha amylase activity, for example, enzymes capable ofhydrolyzing starch to sugars. Unlike many known amylases, the exemplaryamylase of the invention, set forth in SEQ ID NO:2, is not acalcium-dependent enzyme.

It is highly desirable to be able to decrease the Ca2+ dependency of analpha amylase. Accordingly, one aspect of the invention provides anamylase enzyme that has a decreased Ca2+ dependency as compared tocommercial or parent amylases. Decreased Ca2+ dependency will in generalhave the functional consequence that the variant exhibits a satisfactoryamylolytic activity in the presence of a lower concentration of calciumion in the extraneous medium than is necessary for a commercial orparent enzyme. It will further often have the consequence that thevariant is less sensitive to calcium ion-depleting conditions such asthose obtained in media containing calcium-complexing agents (such ascertain detergent builders).

The polynucleotides of the invention have been identified as encodingpolypeptides having alpha amylase activity. An exemplary alpha amylaseenzyme of the invention is shown in SEQ ID NO:2, also referred to hereinas SEQ ID NO:2. Such amylases of the invention are particularly usefulin corn-wet milling processes, detergents, baking processes, beveragesand in oilfields (fuel ethanol).

Alterations in properties which may be achieved in variants of theinvention are alterations in, e.g., substrate specificity, substratebinding, substrate cleavage pattern, thermal stability, pH/activityprofile, pH/stability profile, such as increased stability at low (e.g.pH<6, in particular pH<5) or high (e.g. pH>9) pH values], stabilitytowards oxidation, Ca2+ dependency, specific activity, and otherproperties of interest. For instance, the alteration may result in avariant which, as compared to the parent amylase, has a reduced Ca2+dependency and/or an altered pH/activity profile.

Corn wet milling is a process which produces corn oil, gluten meal,gluten feed and starch. Amylases of the invention, including SEQ IDNO:2, are used in the liquefaction of starch and glucoamylase is used insaccharification, producing glucose. The properties of the amylases ofthe present invention are unique in that they allow production ofliquefied syrups which can be converted to higher dextrose levels than aconventional Bacillus amylase liquefied syrup. As can be seen in FIGS. 6a-6 b and in the Examples, the molecular weight profile of liquefiedstarch produced by commercial amylases derived from Bacilluslicheniformis and Bacillus stearothermophilus exhibit a bimodaldistribution with a primary peak at 1000-2000 MW representingapproximately 60% of the mass with a secondary peak at 30,000-40,000 MW.In addition, there is a substantial fraction at greater than 100,000 MW.The amylases of the invention exhibit a homogeneous MW distributioncentered at 1000-2000 MW with less than 10% of the mass greater than25,000 MW. The higher MW oligosaccharides are not fully converted toglucose during saccharification. Consequently, the commercial amylaseswill contain less dextrose than saccharified syrups from theliquefaction process carried out by amylase enzymes of the presentinvention, such as that represented in SEQ ID NO:2 and functionalequivalents thereof.

Maltodextrins are utilized in a wide variety of food and coatingapplications. Amylases from Archeal sources generate an extremelyuniform maltodextrin composition (see also Leveque et al., Enzyme andMicrobial Technology 26:3-14, 2000, herein incorporated by reference).The use of the amylases of the invention to liquefy corn starch resultsin a uniform maltodextrin composition. The liquefaction can be performedat a pH of about 4.5-6.5, and preferably around pH 5.0 and attemperatures of up to 105 degrees C. or higher.

In addition to the benefits demonstrated in saccharification, theliquefied syrups can be carbon treated, spray dried and utilized as foodadditives, thickeners, low caloric bulking agents, film forming agents,etc. It is anticipated (but not yet proven) that the homogenousmolecular weight profile maltodextrins will have performance advantagesvs. the bimodal distribution maltodextrins produced by the conventionalBaccilus enzymes.

“Liquefaction” or “liquefy” means a process by which starch is convertedto shorter chain and less viscous dextrins. Generally, this processinvolves gelatinization of starch simultaneously with or followed by theaddition of alpha amylase. In commercial processes, it is preferred thatthe granular starch is derived from a source comprising corn, wheat,milo, sorghum, rye or bulgher. However, the present invention applies toany grain starch source which is useful in liquefaction, e.g., any othergrain or vegetable source known to produce starch suitable forliquefaction.

“Granular starch” or “starch granules” means a water-insoluble componentof edible grains which remains after removal of the hull, fiber,protein, fat, germ, and solubles through the steeping, mechanicalcracking, separations, screening, countercurrent rinsing andcentrifugation steps typical of the grain wet-milling process. Granularstarch comprises intact starch granules containing, almost exclusively,packed starch molecules (i.e., amylopectin and amylose). In corn, thegranular starch component comprises about 99% starch; the remaining 1%being comprised of protein, fat, ash, fiber and trace components tightlyassociated with the granules. The packing structure of granular starchseverely retards the ability of .alpha.-amylase to hydrolyze starch.Gelatinization of the starch is utilized to disrupt the granules to forma soluble starch solution and facilitate enzymatic hydrolysis.

“Starch solution” means the water soluble gelatinized starch whichresults from heating granular starch. Upon heating of the granules toabove about 72 degrees C., granular starch dissociates to form anaqueous mixture of loose starch molecules. This mixture comprising, forexample, about 75% amylopectin and 25% amylose in yellow dent corn formsa viscous solution in water. In commercial processes to form glucose orfructose, it is the starch solution which is liquefied to form a solubledextrin solution. “alpha amylase” means an enzymatic activity whichcleaves or hydrolyzes the alpha (1-4) glycosidic bond, e.g., that instarch, amylopectin or amylose polymers. Suitable alpha amylases are thenaturally occurring alpha amylases as well as recombinant or mutantamylases which are useful in liquefaction of starch. Techniques forproducing variant amylases having activity at a pH or temperature, forexample, that is different from the wild-type amylase, are includedherein.

The temperature range of the liquefaction is generally any liquefactiontemperature which is known to be effective in liquefying starch.Preferably, the temperature of the starch is between about 80 degrees C.to about 115 degrees C., more preferably from about 100 degrees C. toabout 110 degrees C., and most preferably from about 105 degrees C. toabout 108 degrees C.

In one embodiment, the signal sequences of the invention are identifiedfollowing identification of novel amylase polypeptides. The pathways bywhich proteins are sorted and transported to their proper cellularlocation are often referred to as protein targeting pathways. One of themost important elements in all of these targeting systems is a shortamino acid sequence at the amino terminus of a newly synthesizedpolypeptide called the signal sequence. This signal sequence directs aprotein to its appropriate location in the cell and is removed duringtransport or when the protein reaches its final destination. Mostlysosomal, membrane, or secreted proteins have an amino-terminal signalsequence that marks them for translocation into the lumen of theendoplasmic reticulum. More than 100 signal sequences for proteins inthis group have been determined. The sequences vary in length from 13 to36 amino acid residues. Various methods of recognition of signalsequences are known to those of skill in the art. In one embodiment, thepeptides are identified by a method referred to as SignalP. SignalP usesa combined neural network which recognizes both signal peptides andtheir cleavage sites. (Nielsen, H., Engelbrecht, J., Brunalk, S., vonHeijne, G., “Identification of prokaryotic and eukaryotic signalpeptides and prediction of their cleavage sites.” Protein Engineering,vol. 10, no. 1, p. 1-6 (1997), hereby incorporated by reference.) Itshould be understood that some of the amylases of the invention may nothave signal sequences. It may be desirable to include a nucleic acidsequence encoding a signal sequence from one amylase operably linked toa nucleic acid sequence of a different amylase or, optionally, a signalsequence from a non-amylase protein may be desired.

The phrases “nucleic acid” or “nucleic acid sequence” as used hereinrefer to an oligonucleotide, nucleotide, polynucleotide, or to afragment of any of these, to DNA or RNA of genomic or synthetic originwhich may be single-stranded or double-stranded and may represent asense or antisense strand, to peptide nucleic acid (PNA), or to anyDNA-like or RNA-like material, natural or synthetic in origin.

A “coding sequence of” or a “nucleotide sequence encoding” a particularpolypeptide or protein, is a nucleic acid sequence which is transcribedand translated into a polypeptide or protein when placed under thecontrol of appropriate regulatory sequences.

The term “gene” means the segment of DNA involved in producing apolypeptide chain; it includes regions preceding and following thecoding region (leader and trailer) as well as, where applicable,intervening sequences (introns) between individual coding segments(exons).

“Amino acid” or “amino acid sequence” as used herein refer to anoligopeptide, peptide, polypeptide, or protein sequence, or to afragment, portion, or subunit of any of these, and to naturallyoccurring or synthetic molecules.

The term “polypeptide” as used herein, refers to amino acids joined toeach other by peptide bonds or modified peptide bonds, i.e., peptideisosteres, and may contain modified amino acids other than the 20gene-encoded amino acids. The polypeptides may be modified by eithernatural processes, such as post-translational processing, or by chemicalmodification techniques which are well known in the art. Modificationscan occur anywhere in the polypeptide, including the peptide backbone,the amino acid side-chains and the amino or carboxyl termini. It will beappreciated that the same type of modification may be present in thesame or varying degrees at several sites in a given polypeptide. Also agiven polypeptide may have many types of modifications. Modificationsinclude acetylation, acylation, ADP-ribosylation, amidation, covalentattachment of flavin, covalent attachment of a heme moiety, covalentattachment of a nucleotide or nucleotide derivative, covalent attachmentof a lipid or lipid derivative, covalent attachment of aphosphytidylinositol, cross-linking cyclization, disulfide bondformation, demethylation, formation of covalent cross-links, formationof cysteine, formation of pyroglutamate, formylation,gamma-carboxylation, glycosylation, GPI anchor formation, hydroxylation,iodination, methylation, myristolyation, oxidation, pergylation,proteolytic processing, phosphorylation, prenylation, racemization,selenoylation, sulfation, and transfer-RNA mediated addition of aminoacids to protein such as arginylation. (See Creighton, T.E.,Proteins—Structure and Molecular Properties 2nd Ed., W.H. Freeman andCompany, New York (1993); Posttranslational Covalent Modification ofProteins, B. C. Johnson, Ed., Academic Press, New York, pp. 1-12(1983)).

As used herein, the term “isolated” means that the material is removedfrom its original environment (e.g., the natural environment if it isnaturally occurring). For example, a naturally-occurring polynucleotideor polypeptide present in a living animal is not isolated, but the samepolynucleotide or polypeptide, separated from some or all of thecoexisting materials in the natural system, is isolated. Suchpolynucleotides could be part of a vector and/or such polynucleotides orpolypeptides could be part of a composition, and still be isolated inthat such vector or composition is not part of its natural environment.

As used herein, the term “purified” does not require absolute purity;rather, it is intended as a relative definition. Individual nucleicacids obtained from a library have been conventionally purified toelectrophoretic homogeneity. The sequences obtained from these clonescould not be obtained directly either from the library or from totalhuman DNA. The purified nucleic acids of the invention have beenpurified from the remainder of the genomic DNA in the organism by atleast 104-106 fold. However, the term “purified” also includes nucleicacids which have been purified from the remainder of the genomic DNA orfrom other sequences in a library or other environment by at least oneorder of magnitude, typically two or three orders, and more typicallyfour or five orders of magnitude.

As used herein, the term “recombinant” means that the nucleic acid isadjacent to a “backbone” nucleic acid to which it is not adjacent in itsnatural environment. Additionally, to be “enriched” the nucleic acidswill represent 5% or more of the number of nucleic acid inserts in apopulation of nucleic acid backbone molecules. Backbone moleculesaccording to the invention include nucleic acids such as expressionvectors, self-replicating nucleic acids, viruses, integrating nucleicacids, and other vectors or nucleic acids used to maintain or manipulatea nucleic acid insert of interest. Typically, the enriched nucleic acidsrepresent 15% or more of the number of nucleic acid inserts in thepopulation of recombinant backbone molecules. More typically, theenriched nucleic acids represent 50% or more of the number of nucleicacid inserts in the population of recombinant backbone molecules. In aone embodiment, the enriched nucleic acids represent 90% or more of thenumber of nucleic acid inserts in the population of recombinant backbonemolecules.

“Recombinant” polypeptides or proteins refer to polypeptides or proteinsproduced by recombinant DNA techniques; i.e., produced from cellstransformed by an exogenous DNA construct encoding the desiredpolypeptide or protein. “Synthetic” polypeptides or protein are thoseprepared by chemical synthesis. Solid-phase chemical peptide synthesismethods can also be used to synthesize the polypeptide or fragments ofthe invention. Such method have been known in the art since the early1960's (Merrifield, R. B., J. Am. Chem. Soc., 85:2149-2154, 1963) (Seealso Stewart, J. M. and Young, J. D., Solid Phase Peptide Synthesis, 2ndEd., Pierce Chemical Co., Rockford, Ill., pp. 11-12)) and have recentlybeen employed in commercially available laboratory peptide design andsynthesis kits (Cambridge Research Biochemicals). Such commerciallyavailable laboratory kits have generally utilized the teachings of H. M.Geysen et al, Proc. Natl. Acad. Sci., USA, 81:3998 (1984) and providefor synthesizing peptides upon the tips of a multitude of “rods” or“pins” all of which are connected to a single plate. When such a systemis utilized, a plate of rods or pins is inverted and inserted into asecond plate of corresponding wells or reservoirs, which containsolutions for attaching or anchoring an appropriate amino acid to thepin's or rod's tips. By repeating such a process step, i.e., invertingand inserting the rod's and pin's tips into appropriate solutions, aminoacids are built into desired peptides. In addition, a number ofavailable FMOC peptide synthesis systems are available. For example,assembly of a polypeptide or fragment can be carried out on a solidsupport using an Applied Biosystems, Inc. Model 431A automated peptidesynthesizer. Such equipment provides ready access to the peptides of theinvention, either by direct synthesis or by synthesis of a series offragments that can be coupled using other known techniques.

A promoter sequence is “operably linked to” a coding sequence when RNApolymerase which initiates transcription at the promoter will transcribethe coding sequence into mRNA.

“Plasmids” are designated by a lower case “p” preceded and/or followedby capital letters and/or numbers. The starting plasmids herein areeither commercially available, publicly available on an unrestrictedbasis, or can be constructed from available plasmids in accord withpublished procedures. In addition, equivalent plasmids to thosedescribed herein are known in the art and will be apparent to theordinarily skilled artisan.

“Digestion” of DNA refers to catalytic cleavage of the DNA with arestriction enzyme that acts only at certain sequences in the DNA. Thevarious restriction enzymes used herein are commercially available andtheir reaction conditions, cofactors and other requirements were used aswould be known to the ordinarily skilled artisan. For analyticalpurposes, typically 1 μg of plasmid or DNA fragment is used with about 2units of enzyme in about 20 μl of buffer solution. For the purpose ofisolating DNA fragments for plasmid construction, typically 5 to 50 μgof DNA are digested with 20 to 250 units of enzyme in a larger volume.Appropriate buffers and substrate amounts for particular restrictionenzymes are specified by the manufacturer. Incubation times of about 1hour at 37° C. are ordinarily used, but may vary in accordance with thesupplier's instructions. After digestion, gel electrophoresis may beperformed to isolate the desired fragment.

“Oligonucleotide” refers to either a single stranded polydeoxynucleotideor two complementary polydeoxynucleotide strands which may be chemicallysynthesized. Such synthetic oligonucleotides have no 5′ phosphate andthus will not ligate to another oligonucleotide without adding aphosphate with an ATP in the presence of a kinase. A syntheticoligonucleotide will ligate to a fragment that has not beendephosphorylated.

The phrase “substantially identical” in the context of two nucleic acidsor polypeptides, refers to two or more sequences that have at least 50%,60%, 70%, 80%, and in some aspects 90-95% nucleotide or amino acidresidue identity, when compared and aligned for maximum correspondence,as measured using one of the known sequence comparison algorithms or byvisual inspection. Typically, the substantial identity exists over aregion of at least about 100 residues, and most commonly the sequencesare substantially identical over at least about 150-200 residues. Insome embodiments, the sequences are substantially identical over theentire length of the coding regions.

Additionally a “substantially identical” amino acid sequence is asequence that differs from a reference sequence by one or moreconservative or non-conservative amino acid substitutions, deletions, orinsertions, particularly when such a substitution occurs at a site thatis not the active site of the molecule, and provided that thepolypeptide essentially retains its functional properties. Aconservative amino acid substitution, for example, substitutes one aminoacid for another of the same class (e.g., substitution of onehydrophobic amino acid, such as isoleucine, valine, leucine, ormethionine, for another, or substitution of one polar amino acid foranother, such as substitution of arginine for lysine, glutamic acid foraspartic acid or glutamine for asparagine). One or more amino acids canbe deleted, for example, from an alpha amylase polypeptide, resulting inmodification of the structure of the polypeptide, without significantlyaltering its biological activity. For example, amino- orcarboxyl-terminal amino acids that are not required for alpha amylasebiological activity can be removed. Modified polypeptide sequences ofthe invention can be assayed for alpha amylase biological activity byany number of methods, including contacting the modified polypeptidesequence with an alpha amylase substrate and determining whether themodified polypeptide decreases the amount of specific substrate in theassay or increases the bioproducts of the enzymatic reaction of afunctional alpha amylase polypeptide with the substrate.

“Fragments” as used herein are a portion of a naturally occurringprotein which can exist in at least two different conformations.Fragments can have the same or substantially the same amino acidsequence as the naturally occurring protein. “Substantially the same”means that an amino acid sequence is largely, but not entirely, thesame, but retains at least one functional activity of the sequence towhich it is related. In general two amino acid sequences are“substantially the same” or “substantially homologous” if they are atleast about 85% identical. Fragments which have different threedimensional structures as the naturally occurring protein are alsoincluded. An example of this, is a “pro-form” molecule, such as a lowactivity proprotein that can be modified by cleavage to produce a matureenzyme with significantly higher activity.

“Hybridization” refers to the process by which a nucleic acid strandjoins with a complementary strand through base pairing. Hybridizationreactions can be sensitive and selective so that a particular sequenceof interest can be identified even in samples in which it is present atlow concentrations. Suitably stringent conditions can be defined by, forexample, the concentrations of salt or formamide in the prehybridizationand hybridization solutions, or by the hybridization temperature, andare well known in the art. In particular, stringency can be increased byreducing the concentration of salt, increasing the concentration offormamide, or raising the hybridization temperature.

For example, hybridization under high stringency conditions could occurin about 50% formamide at about 37° C. to 42° C. Hybridization couldoccur under reduced stringency conditions in about 35% to 25% formamideat about 30° C. to 35° C. In particular, hybridization could occur underhigh stringency conditions at 42° C. in 50% formamide, 5×SSPE, 0.3% SDS,and 200 n/ml sheared and denatured salmon sperm DNA. Hybridization couldoccur under reduced stringency conditions as described above, but in 35%formamide at a reduced temperature of 35° C. The temperature rangecorresponding to a particular level of stringency can be furthernarrowed by calculating the purine to pyrimidine ratio of the nucleicacid of interest and adjusting the temperature accordingly. Variationson the above ranges and conditions are well known in the art.

The term “variant” refers to polynucleotides or polypeptides of theinvention modified at one or more base pairs, codons, introns, exons, oramino acid residues (respectively) yet still retain the biologicalactivity of an alpha amylase of the invention. Variants can be producedby any number of means included methods such as, for example,error-prone PCR, shuffling, oligonucleotide-directed mutagenesis,assembly PCR, sexual PCR mutagenesis, in vivo mutagenesis, cassettemutagenesis, recursive ensemble mutagenesis, exponential ensemblemutagenesis, site-specific mutagenesis, gene reassembly, GSSM™ and anycombination thereof. Techniques for producing variant amylases havingactivity at a pH or temperature, for example, that is different from thewild-type amylase, are included herein.

Enzymes are highly selective catalysts. Their hallmark is the ability tocatalyze reactions with exquisite stereo-, regio-, andchemo-selectivities that are unparalleled in conventional syntheticchemistry. Moreover, enzymes are remarkably versatile. They can betailored to function in organic solvents, operate at extreme pHs (forexample, high pHs and low pHs) extreme temperatures (for example, hightemperatures and low temperatures), extreme salinity levels (forexample, high salinity and low salinity), and catalyze reactions withcompounds that are structurally unrelated to their natural,physiological substrates.

Enzymes are reactive toward a wide range of natural and unnaturalsubstrates, thus enabling the modification of virtually any organic leadcompound. Moreover, unlike traditional chemical catalysts, enzymes arehighly enantio- and regio-selective. The high degree of functional groupspecificity exhibited by enzymes enables one to keep track of eachreaction in a synthetic sequence leading to a new active compound.Enzymes are also capable of catalyzing many diverse reactions unrelatedto their physiological function in nature. For example, peroxidasescatalyze the oxidation of phenols by hydrogen peroxide. Peroxidases canalso catalyze hydroxylation reactions that are not related to the nativefunction of the enzyme. Other examples are proteases which catalyze thebreakdown of polypeptides. In organic solution some proteases can alsoacylate sugars, a function unrelated to the native function of theseenzymes.

In one aspect, the invention includes a method for liquefying a starchcontaining composition comprising contacting the starch with apolypeptide of the invention (e.g., a purified polypeptide selected frompolypeptides having an amino acid sequence selected from the groupconsisting of: SEQ ID NO:2; variants having at least about 50% homologyto at least one of SEQ ID NO:2, over a region of at least about 100residues, as determined by analysis with a sequence comparison algorithmor by visual inspection; sequences complementary to SEQ ID NO:2; andsequences complementary to variants having at least about 50% homologyto SEQ ID NO:2 over a region of at least about 100 residues, asdetermined by analysis with a sequence comparison algorithm or by visualinspection; and polypeptides having at least 10 consecutive amino acidsof a polypeptide having a sequence selected from the group consisting ofSEQ ID NO:2). In one preferred embodiment, the polypeptide is set forthin SEQ ID NO:2. The starch may be from a material selected from rice,germinated rice, corn, barley, wheat, legumes and sweet potato. Aglucose syrup produced by the method of the invention is included hereinand is described in the examples. Such a syrup can be a maltose syrup, aglucose syrup, or a combination thereof. In particular, the syrupsproduced using the amylases of the invention there is a higher level ofDP2 fraction and a higher level of DP3 (maltotriose and/or panose) andless of the greater than DP7 fragments as compared to the syrupsproduced by commercial enzymes (see Example 5). This is consistent withthe liquefaction profile since less of the large fragments are in theinvention liquefied syrups (see Example 5).

The invention also provides a method for removing starch containingstains from a material comprising contacting the material with apolypeptide of the invention. In one aspect, the invention provides amethod for washing an object comprising contacting the object with apolypeptide of the invention under conditions sufficient for washing. Apolypeptide of the invention may be included as a detergent additive forexample. The invention also includes a method for textile desizingcomprising contacting the textile with a polypeptide of the inventionunder conditions sufficient for desizing.

The invention also provides a method of reducing the staling of bakeryproducts comprising addition of a polypeptide of the invention to thebakery product, prior to baking.

The invention also provides a method for the treatment oflignocellulosic fibers, wherein the fibers are treated with apolypeptide of the invention, in an amount which is efficient forimproving the fiber properties. The invention includes a for enzymaticdeinking of recycled paper pulp, wherein the polypeptide is applied inan amount which is efficient for effective deinking of the fibersurface.

Any of the methods described herein include the possibility of theaddition of a second alpha amylase or a beta amylase or a combinationthereof. Commercial amylases or other enzymes suitable for use incombination with an enzyme of the invention are known to those of skillin the art.

The invention also includes a method of increasing the flow ofproduction fluids from a subterranean formation by removing a viscous,starch-containing, damaging fluid formed during production operationsand found within the subterranean formation which surrounds a completedwell bore comprising allowing production fluids to flow from the wellbore; reducing the flow of production fluids from the formation belowexpected flow rates; formulating an enzyme treatment by blendingtogether an aqueous fluid and a polypeptide of the invention; pumpingthe enzyme treatment to a desired location within the well bore;allowing the enzyme treatment to degrade the viscous, starch-containing,damaging fluid, whereby the fluid can be removed from the subterraneanformation to the well surface; and wherein the enzyme treatment iseffective to attack the alpha glucosidic linkages in thestarch-containing fluid.

The present invention exploits the unique catalytic properties ofenzymes. Whereas the use of biocatalysts (i.e., purified or crudeenzymes, non-living or living cells) in chemical transformationsnormally requires the identification of a particular biocatalyst thatreacts with a specific starting compound, the present invention usesselected biocatalysts and reaction conditions that are specific forfunctional groups that are present in many starting compounds.

Each biocatalyst is specific for one functional group, or severalrelated functional groups, and can react with many starting compoundscontaining this functional group.

The biocatalytic reactions produce a population of derivatives from asingle starting compound. These derivatives can be subjected to anotherround of biocatalytic reactions to produce a second population ofderivative compounds. Thousands of variations of the original compoundcan be produced with each iteration of biocatalytic derivatization.

Enzymes react at specific sites of a starting compound without affectingthe rest of the molecule, a process which is very difficult to achieveusing traditional chemical methods. This high degree of biocatalyticspecificity provides the means to identify a single active compoundwithin the library. The library is characterized by the series ofbiocatalytic reactions used to produce it, a so-called “biosynthetichistory”. Screening the library for biological activities and tracingthe biosynthetic history identifies the specific reaction sequenceproducing the active compound. The reaction sequence is repeated and thestructure of the synthesized compound determined. This mode ofidentification, unlike other synthesis and screening approaches, doesnot require immobilization technologies, and compounds can besynthesized and tested free in solution using virtually any type ofscreening assay. It is important to note, that the high degree ofspecificity of enzyme reactions on functional groups allows for the“tracking” of specific enzymatic reactions that make up thebiocatalytically produced library.

Many of the procedural steps are performed using robotic automationenabling the execution of many thousands of biocatalytic reactions andscreening assays per day as well as ensuring a high level of accuracyand reproducibility. As a result, a library of derivative compounds canbe produced in a matter of weeks which would take years to produce usingcurrent chemical methods. (For further teachings on modification ofmolecules, including small molecules, see PCT/US94/09174, hereinincorporated by reference in its entirety).

In one aspect, the present invention provides a non-stochastic methodtermed synthetic gene reassembly, that is somewhat related to stochasticshuffling, save that the nucleic acid building blocks are not shuffledor concatenated or chimerized randomly, but rather are assemblednon-stochastically.

The synthetic gene reassembly method does not depend on the presence ofa high level of homology between polynucleotides to be shuffled. Theinvention can be used to non-stochastically generate libraries (or sets)of progeny molecules comprised of over 10¹⁰⁰ different chimeras.Conceivably, synthetic gene reassembly can even be used to generatelibraries comprised of over 10¹⁰⁰⁰ different progeny chimeras.

Thus, in one aspect, the invention provides a non-stochastic method ofproducing a set of finalized chimeric nucleic acid molecules having anoverall assembly order that is chosen by design, which method iscomprised of the steps of generating by design a plurality of specificnucleic acid building blocks having serviceable mutually compatibleligatable ends, and assembling these nucleic acid building blocks, suchthat a designed overall assembly order is achieved.

The mutually compatible ligatable ends of the nucleic acid buildingblocks to be assembled are considered to be “serviceable” for this typeof ordered assembly if they enable the building blocks to be coupled inpredetermined orders. Thus, in one aspect, the overall assembly order inwhich the nucleic acid building blocks can be coupled is specified bythe design of the ligatable ends and, if more than one assembly step isto be used, then the overall assembly order in which the nucleic acidbuilding blocks can be coupled is also specified by the sequential orderof the assembly step(s). In a one embodiment of the invention, theannealed building pieces are treated with an enzyme, such as a ligase(e.g., T4 DNA ligase) to achieve covalent bonding of the buildingpieces.

In a another embodiment, the design of nucleic acid building blocks isobtained upon analysis of the sequences of a set of progenitor nucleicacid templates that serve as a basis for producing a progeny set offinalized chimeric nucleic acid molecules. These progenitor nucleic acidtemplates thus serve as a source of sequence information that aids inthe design of the nucleic acid building blocks that are to bemutagenized, i.e. chimerized or shuffled.

In one exemplification, the invention provides for the chimerization ofa family of related genes and their encoded family of related products.In a particular exemplification, the encoded products are enzymes. Thealpha amylases of the present invention can be mutagenized in accordancewith the methods described herein.

Thus according to one aspect of the invention, the sequences of aplurality of progenitor nucleic acid templates (e.g., polynucleotides ofSEQ ID NO:1 nucleic acid sequences) are aligned in order to select oneor more demarcation points, which demarcation points can be located atan area of homology. The demarcation points can be used to delineate theboundaries of nucleic acid building blocks to be generated. Thus, thedemarcation points identified and selected in the progenitor moleculesserve as potential chimerization points in the assembly of the progenymolecules.

Typically a serviceable demarcation point is an area of homology(comprised of at least one homologous nucleotide base) shared by atleast two progenitor templates, but the demarcation point can be an areaof homology that is shared by at least half of the progenitor templates,at least two thirds of the progenitor templates, at least three fourthsof the progenitor templates, and preferably at almost all of theprogenitor templates. Even more preferably still a serviceabledemarcation point is an area of homology that is shared by all of theprogenitor templates.

In a one embodiment, the gene reassembly process is performedexhaustively in order to generate an exhaustive library. In other words,all possible ordered combinations of the nucleic acid building blocksare represented in the set of finalized chimeric nucleic acid molecules.At the same time, the assembly order (i.e. the order of assembly of eachbuilding block in the 5′ to 3 sequence of each finalized chimericnucleic acid) in each combination is by design (or non-stochastic).Because of the non-stochastic nature of the method, the possibility ofunwanted side products is greatly reduced.

In another embodiment, the method provides that the gene reassemblyprocess is performed systematically, for example to generate asystematically compartmentalized library, with compartments that can bescreened systematically, e.g., one by one. In other words the inventionprovides that, through the selective and judicious use of specificnucleic acid building blocks, coupled with the selective and judicioususe of sequentially stepped assembly reactions, an experimental designcan be achieved where specific sets of progeny products are made in eachof several reaction vessels. This allows a systematic examination andscreening procedure to be performed. Thus, it allows a potentially verylarge number of progeny molecules to be examined systematically insmaller groups.

Because of its ability to perform chimerizations in a manner that ishighly flexible yet exhaustive and systematic as well, particularly whenthere is a low level of homology among the progenitor molecules, theinstant invention provides for the generation of a library (or set)comprised of a large number of progeny molecules. Because of thenon-stochastic nature of the instant gene reassembly invention, theprogeny molecules generated preferably comprise a library of finalizedchimeric nucleic acid molecules having an overall assembly order that ischosen by design. In a particularly embodiment, such a generated libraryis comprised of greater than 10³ to greater than 10¹⁰⁰⁰ differentprogeny molecular species.

In one aspect, a set of finalized chimeric nucleic acid molecules,produced as described is comprised of a polynucleotide encoding apolypeptide. According to one embodiment, this polynucleotide is a gene,which may be a man-made gene. According to another embodiment, thispolynucleotide is a gene pathway, which may be a man-made gene pathway.The invention provides that one or more man-made genes generated by theinvention may be incorporated into a man-made gene pathway, such aspathway operable in a eukaryotic organism (including a plant).

In another exemplification, the synthetic nature of the step in whichthe building blocks are generated allows the design and introduction ofnucleotides (e.g., one or more nucleotides, which may be, for example,codons or introns or regulatory sequences) that can later be optionallyremoved in an in vitro process (e.g., by mutagenesis) or in an in vivoprocess (e.g., by utilizing the gene splicing ability of a hostorganism). It is appreciated that in many instances the introduction ofthese nucleotides may also be desirable for many other reasons inaddition to the potential benefit of creating a serviceable demarcationpoint.

Thus, according to another embodiment, the invention provides that anucleic acid building block can be used to introduce an intron. Thus,the invention provides that functional introns may be introduced into aman-made gene of the invention. The invention also provides thatfunctional introns may be introduced into a man-made gene pathway of theinvention. Accordingly, the invention provides for the generation of achimeric polynucleotide that is a man-made gene containing one (or more)artificially introduced intron(s).

Accordingly, the invention also provides for the generation of achimeric polynucleotide that is a man-made gene pathway containing one(or more) artificially introduced intron(s). Preferably, theartificially introduced intron(s) are functional in one or more hostcells for gene splicing much in the way that naturally-occurring intronsserve functionally in gene splicing. The invention provides a process ofproducing man-made intron-containing polynucleotides to be introducedinto host organisms for recombination and/or splicing.

A man-made gene produced using the invention can also serve as asubstrate for recombination with another nucleic acid. Likewise, aman-made gene pathway produced using the invention can also serve as asubstrate for recombination with another nucleic acid. In a preferredinstance, the recombination is facilitated by, or occurs at, areas ofhomology between the man-made, intron-containing gene and a nucleicacid, which serves as a recombination partner. In a particularlypreferred instance, the recombination partner may also be a nucleic acidgenerated by the invention, including a man-made gene or a man-made genepathway. Recombination may be facilitated by or may occur at areas ofhomology that exist at the one (or more) artificially introducedintron(s) in the man-made gene.

The synthetic gene reassembly method of the invention utilizes aplurality of nucleic acid building blocks, each of which preferably hastwo ligatable ends. The two ligatable ends on each nucleic acid buildingblock may be two blunt ends (i.e. each having an overhang of zeronucleotides), or preferably one blunt end and one overhang, or morepreferably still two overhangs.

A useful overhang for this purpose may be a 3′ overhang or a 5′overhang. Thus, a nucleic acid building block may have a 3′ overhang oralternatively a 5′ overhang or alternatively two 3′ overhangs oralternatively two 5′ overhangs. The overall order in which the nucleicacid building blocks are assembled to form a finalized chimeric nucleicacid molecule is determined by purposeful experimental design and is notrandom.

According to one preferred embodiment, a nucleic acid building block isgenerated by chemical synthesis of two single-stranded nucleic acids(also referred to as single-stranded oligos) and contacting them so asto allow them to anneal to form a double-stranded nucleic acid buildingblock.

A double-stranded nucleic acid building block can be of variable size.The sizes of these building blocks can be small or large. Preferredsizes for building block range from 1 base pair (not including anyoverhangs) to 100,000 base pairs (not including any overhangs). Otherpreferred size ranges are also provided, which have lower limits of from1 bp to 10,000 bp (including every integer value in between), and upperlimits of from 2 bp to 100,000 bp (including every integer value inbetween).

Many methods exist by which a double-stranded nucleic acid buildingblock can be generated that is serviceable for the invention; and theseare known in the art and can be readily performed by the skilledartisan.

According to one embodiment, a double-stranded nucleic acid buildingblock is generated by first generating two single stranded nucleic acidsand allowing them to anneal to form a double-stranded nucleic acidbuilding block. The two strands of a double-stranded nucleic acidbuilding block may be complementary at every nucleotide apart from anythat form an overhang; thus containing no mismatches, apart from anyoverhang(s). According to another embodiment, the two strands of adouble-stranded nucleic acid building block are complementary at fewerthan every nucleotide apart from any that form an overhang. Thus,according to this embodiment, a double-stranded nucleic acid buildingblock can be used to introduce codon degeneracy. Preferably the codondegeneracy is introduced using the site-saturation mutagenesis describedherein, using one or more N,N,G/T cassettes or alternatively using oneor more N,N,N cassettes.

The in vivo recombination method of the invention can be performedblindly on a pool of unknown hybrids or alleles of a specificpolynucleotide or sequence. However, it is not necessary to know theactual DNA or RNA sequence of the specific polynucleotide.

The approach of using recombination within a mixed population of genescan be useful for the generation of any useful proteins, for example,interleukin I, antibodies, tPA and growth hormone. This approach may beused to generate proteins having altered specificity or activity. Theapproach may also be useful for the generation of hybrid nucleic acidsequences, for example, promoter regions, introns, exons, enhancersequences, 31 untranslated regions or 51 untranslated regions of genes.Thus this approach may be used to generate genes having increased ratesof expression. This approach may also be useful in the study ofrepetitive DNA sequences. Finally, this approach may be useful to mutateribozymes or aptamers.

In one aspect the invention described herein is directed to the use ofrepeated cycles of reductive reassortment, recombination and selectionwhich allow for the directed molecular evolution of highly complexlinear sequences, such as DNA, RNA or proteins through recombination.

In vivo shuffling of molecules is useful in providing variants and canbe performed utilizing the natural property of cells to recombinemultimers. While recombination in vivo has provided the major naturalroute to molecular diversity, genetic recombination remains a relativelycomplex process that involves 1) the recognition of homologies; 2)strand cleavage, strand invasion, and metabolic steps leading to theproduction of recombinant chiasma; and finally 3) the resolution ofchiasma into discrete recombined molecules. The formation of the chiasmarequires the recognition of homologous sequences.

In another embodiment, the invention includes a method for producing ahybrid polynucleotide from at least a first polynucleotide and a secondpolynucleotide. The invention can be used to produce a hybridpolynucleotide by introducing at least a first polynucleotide and asecond polynucleotide which share at least one region of partialsequence homology into a suitable host cell. The regions of partialsequence homology promote processes which result in sequencereorganization producing a hybrid polynucleotide. The term “hybridpolynucleotide”, as used herein, is any nucleotide sequence whichresults from the method of the present invention and contains sequencefrom at least two original polynucleotide sequences. Such hybridpolynucleotides can result from intermolecular recombination eventswhich promote sequence integration between DNA molecules. In addition,such hybrid polynucleotides can result from intramolecular reductivereassortment processes which utilize repeated sequences to alter anucleotide sequence within a DNA molecule.

The invention provides a means for generating hybrid polynucleotideswhich may encode biologically active hybrid polypeptides (e.g., hybridalpha amylases). In one aspect, the original polynucleotides encodebiologically active polypeptides. The method of the invention producesnew hybrid polypeptides by utilizing cellular processes which integratethe sequence of the original polynucleotides such that the resultinghybrid polynucleotide encodes a polypeptide demonstrating activitiesderived from the original biologically active polypeptides. For example,the original polynucleotides may encode a particular enzyme fromdifferent microorganisms. An enzyme encoded by a first polynucleotidefrom one organism or variant may, for example, function effectivelyunder a particular environmental condition, e.g. high salinity. Anenzyme encoded by a second polynucleotide from a different organism orvariant may function effectively under a different environmentalcondition, such as extremely high temperatures. A hybrid polynucleotidecontaining sequences from the first and second original polynucleotidesmay encode an enzyme which exhibits characteristics of both enzymesencoded by the original polynucleotides. Thus, the enzyme encoded by thehybrid polynucleotide may function effectively under environmentalconditions shared by each of the enzymes encoded by the first and secondpolynucleotides, e.g., high salinity and extreme temperatures.

Enzymes encoded by the polynucleotides of the invention include, but arenot limited to, hydrolases, such as alpha amylases. A hybrid polypeptideresulting from the method of the invention may exhibit specializedenzyme activity not displayed in the original enzymes. For example,following recombination and/or reductive reassortment of polynucleotidesencoding hydrolase activities, the resulting hybrid polypeptide encodedby a hybrid polynucleotide can be screened for specialized hydrolaseactivities obtained from each of the original enzymes, i.e. the type ofbond on which the hydrolase acts and the temperature at which thehydrolase functions. Thus, for example, the hydrolase may be screened toascertain those chemical functionalities which distinguish the hybridhydrolase from the original hydrolases, such as: (a) amide (peptidebonds), i.e., proteases; (b) ester bonds, i.e., amylases and lipases;(c) acetals, i.e., glycosidases and, for example, the temperature, pH orsalt concentration at which the hybrid polypeptide functions.

Sources of the original polynucleotides may be isolated from individualorganisms (“isolates”), collections of organisms that have been grown indefined media (“enrichment cultures”), or, uncultivated organisms(“environmental samples”). The use of a culture-independent approach toderive polynucleotides encoding novel bioactivities from environmentalsamples is most preferable since it allows one to access untappedresources of biodiversity.

“Environmental libraries” are generated from environmental samples andrepresent the collective genomes of naturally occurring organismsarchived in cloning vectors that can be propagated in suitableprokaryotic hosts. Because the cloned DNA is initially extracteddirectly from environmental samples, the libraries are not limited tothe small fraction of prokaryotes that can be grown in pure culture.Additionally, a normalization of the environmental DNA present in thesesamples could allow more equal representation of the DNA from all of thespecies present in the original sample. This can dramatically increasethe efficiency of finding interesting genes from minor constituents ofthe sample which may be under-represented by several orders of magnitudecompared to the dominant species.

For example, gene libraries generated from one or more uncultivatedmicroorganisms are screened for an activity of interest. Potentialpathways encoding bioactive molecules of interest are first captured inprokaryotic cells in the form of gene expression libraries.Polynucleotides encoding activities of interest are isolated from suchlibraries and introduced into a host cell. The host cell is grown underconditions which promote recombination and/or reductive reassortmentcreating potentially active biomolecules with novel or enhancedactivities.

The microorganisms from which the polynucleotide may be prepared includeprokaryotic microorganisms, such as Eubacteria and Archaebacteria, andlower eukaryotic microorganisms such as fungi, some algae and protozoa.Polynucleotides may be isolated from environmental samples in which casethe nucleic acid may be recovered without culturing of an organism orrecovered from one or more cultured organisms. In one aspect, suchmicroorganisms may be extremophiles, such as hyperthermophiles,psychrophiles, psychrotrophs, halophiles, barophiles and acidophiles.Polynucleotides encoding enzymes isolated from extremophilicmicroorganisms are particularly preferred. Such enzymes may function attemperatures above 100° C. in terrestrial hot springs and deep seathermal vents, at temperatures below 0° C. in arctic waters, in thesaturated salt environment of the Dead Sea, at pH values around 0 incoal deposits and geothermal sulfur-rich springs, or at pH valuesgreater than 11 in sewage sludge. For example, several amylases andlipases cloned and expressed from extremophilic organisms show highactivity throughout a wide range of temperatures and pHs.

Polynucleotides selected and isolated as hereinabove described areintroduced into a suitable host cell. A suitable host cell is any cellwhich is capable of promoting recombination and/or reductivereassortment. The selected polynucleotides are preferably already in avector which includes appropriate control sequences. The host cell canbe a higher eukaryotic cell, such as a mammalian cell, or a lowereukaryotic cell, such as a yeast cell, or preferably, the host cell canbe a prokaryotic cell, such as a bacterial cell. Introduction of theconstruct into the host cell can be effected by calcium phosphatetransfection, DEAE-Dextran mediated transfection, or electroporation(Davis et al., 1986).

As representative examples of appropriate hosts, there may be mentioned:bacterial cells, such as E. coli, Streptomyces, Salmonella typhimurium;fungal cells, such as yeast; insect cells such as Drosophila S2 andSpodoptera Sf9; animal cells such as CHO, COS or Bowes melanoma;adenoviruses; and plant cells. The selection of an appropriate host isdeemed to be within the scope of those skilled in the art from theteachings herein.

With particular references to various mammalian cell culture systemsthat can be employed to express recombinant protein, examples ofmammalian expression systems include the COS-7 lines of monkey kidneyfibroblasts, described in “SV40-transformed simian cells support thereplication of early SV40 mutants” (Gluzman, 1981), and other cell linescapable of expressing a compatible vector, for example, the C127, 3T3,CHO, HeLa and BHK cell lines. Mammalian expression vectors will comprisean origin of replication, a suitable promoter and enhancer, and also anynecessary ribosome binding sites, polyadenylation site, splice donor andacceptor sites, transcriptional termination sequences, and 5′ flankingnontranscribed sequences. DNA sequences derived from the SV40 splice,and polyadenylation sites may be used to provide the requirednontranscribed genetic elements.

Host cells containing the polynucleotides of interest can be cultured inconventional nutrient media modified as appropriate for activatingpromoters, selecting transformants or amplifying genes. The cultureconditions, such as temperature, pH and the like, are those previouslyused with the host cell selected for expression, and will be apparent tothe ordinarily skilled artisan. The clones which are identified ashaving the specified enzyme activity may then be sequenced to identifythe polynucleotide sequence encoding an enzyme having the enhancedactivity.

In another aspect, it is envisioned the method of the present inventioncan be used to generate novel polynucleotides encoding biochemicalpathways from one or more operons or gene clusters or portions thereof.For example, bacteria and many eukaryotes have a coordinated mechanismfor regulating genes whose products are involved in related processes.The genes are clustered, in structures referred to as “gene clusters,”on a single chromosome and are transcribed together under the control ofa single regulatory sequence, including a single promoter whichinitiates transcription of the entire cluster. Thus, a gene cluster is agroup of adjacent genes that are either identical or related, usually asto their function. An example of a biochemical pathway encoded by geneclusters are polyketides. Polyketides are molecules which are anextremely rich source of bioactivities, including antibiotics (such astetracyclines and erythromycin), anti-cancer agents (daunomycin),immunosuppressants (FK506 and rapamycin), and veterinary products(monensin). Many polyketides (produced by polyketide synthases) arevaluable as therapeutic agents. Polyketide synthases are multifunctionalenzymes that catalyze the biosynthesis of an enormous variety of carbonchains differing in length and patterns of functionality andcyclization. Polyketide synthase genes fall into gene clusters and atleast one type (designated type I) of polyketide synthases have largesize genes and enzymes, complicating genetic manipulation and in vitrostudies of these genes/proteins.

Gene cluster DNA can be isolated from different organisms and ligatedinto vectors, particularly vectors containing expression regulatorysequences which can control and regulate the production of a detectableprotein or protein-related array activity from the ligated geneclusters. Use of vectors which have an exceptionally large capacity forexogenous DNA introduction are particularly appropriate for use withsuch gene clusters and are described by way of example herein to includethe f-factor (or fertility factor) of E. coli. This f-factor of E. coliis a plasmid which affect high-frequency transfer of itself duringconjugation and is ideal to achieve and stably propagate large DNAfragments, such as gene clusters from mixed microbial samples. Aparticularly preferred embodiment is to use cloning vectors, referred toas “fosmids” or bacterial artificial chromosome (BAC) vectors. These arederived from E. coli f-factor which is able to stably integrate largesegments of genomic DNA. When integrated with DNA from a mixeduncultured environmental sample, this makes it possible to achieve largegenomic fragments in the form of a stable “environmental DNA library.”Another type of vector for use in the present invention is a cosmidvector. Cosmid vectors were originally designed to clone and propagatelarge segments of genomic DNA. Cloning into cosmid vectors is describedin detail in Sambrook et al., Molecular Cloning: A Laboratory Manual,2nd Ed., Cold Spring Harbor Laboratory Press (1989). Once ligated intoan appropriate vector, two or more vectors containing differentpolyketide synthase gene clusters can be introduced into a suitable hostcell. Regions of partial sequence homology shared by the gene clusterswill promote processes which result in sequence reorganization resultingin a hybrid gene cluster. The novel hybrid gene cluster can then bescreened for enhanced activities not found in the original geneclusters.

Therefore, in a one embodiment, the invention relates to a method forproducing a biologically active hybrid polypeptide and screening such apolypeptide for enhanced activity by:

1) introducing at least a first polynucleotide in operable linkage and asecond polynucleotide in operable linkage, said at least firstpolynucleotide and second polynucleotide sharing at least one region ofpartial sequence homology, into a suitable host cell;

2) growing the host cell under conditions which promote sequencereorganization resulting in a hybrid polynucleotide in operable linkage;

3) expressing a hybrid polypeptide encoded by the hybrid polynucleotide;

4) screening the hybrid polypeptide under conditions which promoteidentification of enhanced biological activity; and

5) isolating the a polynucleotide encoding the hybrid polypeptide.

Methods for screening for various enzyme activities are known to thoseof skill in the art and are discussed throughout the presentspecification. Such methods may be employed when isolating thepolypeptides and polynucleotides of the invention.

As representative examples of expression vectors which may be used,there may be mentioned viral particles, baculovirus, phage, plasmids,phagemids, cosmids, fosmids, bacterial artificial chromosomes, viral DNA(e.g., vaccinia, adenovirus, foul pox virus, pseudorabies andderivatives of SV40), P1-based artifidial chomosomes, yeast plasmids,yeast artificial chromosomes, and any other vectors specific forspecific hosts of interest (such as bacillus, Aspergillus and yeast).Thus, for example, the DNA may be included in any one of a variety ofexpression vectors for expressing a polypeptide. Such vectors includechromosomal, nonchromosomal and synthetic DNA sequences. Large numbersof suitable vectors are known to those of skill in the art, and arecommercially available. The following vectors are provided by way ofexample; Bacterial: pQE vectors (Qiagen), pBLUESCRIPT™ plasmids, pNHvectors, (lambda-ZAP vectors (Stratagene); ptrc99a, pKK223-3, pDR540,pRIT2T (Pharmacia); Eukaryotic: pXT1, pSG5 (Stratagene), pSVK3, pBPV,pMSG, pSVLSV40 (Pharmacia). However, any other plasmid or other vectormay be used so long as they are replicable and viable in the host. Lowcopy number or high copy number vectors may be employed with the presentinvention.

The DNA sequence in the expression vector is operatively linked to anappropriate expression control sequence(s) (promoter) to direct RNAsynthesis. Particular named bacterial promoters include lacI, lacZ, T3,T7, gpt, lambda PR, PL and trp. Eukaryotic promoters include CMVimmediate early, HSV thymidine kinase, early and late SV40, LTRs fromretrovirus, and mouse metallothionein-I. Selection of the appropriatevector and promoter is well within the level of ordinary skill in theart. The expression vector also contains a ribosome binding site fortranslation initiation and a transcription terminator. The vector mayalso include appropriate sequences for amplifying expression. Promoterregions can be selected from any desired gene using chloramphenicoltransferase (CAT) vectors or other vectors with selectable markers. Inaddition, the expression vectors preferably contain one or moreselectable marker genes to provide a phenotypic trait for selection oftransformed host cells such as dihydrofolate reductase or neomycinresistance for eukaryotic cell culture, or such as tetracycline orampicillin resistance in E. coli.

In vivo reassortment is focused on “inter-molecular” processescollectively referred to as “recombination” which in bacteria, isgenerally viewed as a “RecA-dependent” phenomenon. The invention canrely on recombination processes of a host cell to recombine andre-assort sequences, or the cells' ability to mediate reductiveprocesses to decrease the complexity of quasi-repeated sequences in thecell by deletion. This process of “reductive reassortment” occurs by an“intra-molecular”, RecA-independent process.

Therefore, in another aspect of the invention, novel polynucleotides canbe generated by the process of reductive reassortment. The methodinvolves the generation of constructs containing consecutive sequences(original encoding sequences), their insertion into an appropriatevector, and their subsequent introduction into an appropriate host cell.The reassortment of the individual molecular identities occurs bycombinatorial processes between the consecutive sequences in theconstruct possessing regions of homology, or between quasi-repeatedunits. The reassortment process recombines and/or reduces the complexityand extent of the repeated sequences, and results in the production ofnovel molecular species. Various treatments may be applied to enhancethe rate of reassortment. These could include treatment withultra-violet light, or DNA damaging chemicals, and/or the use of hostcell lines displaying enhanced levels of “genetic instability”. Thus thereassortment process may involve homologous recombination or the naturalproperty of quasi-repeated sequences to direct their own evolution.

Repeated or “quasi-repeated” sequences play a role in geneticinstability. In the present invention, “quasi-repeats” are repeats thatare not restricted to their original unit structure. Quasi-repeatedunits can be presented as an array of sequences in a construct;consecutive units of similar sequences. Once ligated, the junctionsbetween the consecutive sequences become essentially invisible and thequasi-repetitive nature of the resulting construct is now continuous atthe molecular level. The deletion process the cell performs to reducethe complexity of the resulting construct operates between thequasi-repeated sequences. The quasi-repeated units provide a practicallylimitless repertoire of templates upon which slippage events can occur.The constructs containing the quasi-repeats thus effectively providesufficient molecular elasticity that deletion (and potentiallyinsertion) events can occur virtually anywhere within thequasi-repetitive units.

When the quasi-repeated sequences are all ligated in the sameorientation, for instance head to tail or vice versa, the cell cannotdistinguish individual units. Consequently, the reductive process canoccur throughout the sequences. In contrast, when for example, the unitsare presented head to head, rather than head to tail, the inversiondelineates the endpoints of the adjacent unit so that deletion formationwill favor the loss of discrete units. Thus, it is preferable with thepresent method that the sequences are in the same orientation. Randomorientation of quasi-repeated sequences will result in the loss ofreassortment efficiency, while consistent orientation of the sequenceswill offer the highest efficiency. However, while having fewer of thecontiguous sequences in the same orientation decreases the efficiency,it may still provide sufficient elasticity for the effective recovery ofnovel molecules. Constructs can be made with the quasi-repeatedsequences in the same orientation to allow higher efficiency.

Sequences can be assembled in a head to tail orientation using any of avariety of methods, including the following:

a) Primers that include a poly-A head and poly-T tail which when madesingle-stranded would provide orientation can be utilized. This isaccomplished by having the first few bases of the primers made from RNAand hence easily removed RNAseH.

b) Primers that include unique restriction cleavage sites can beutilized. Multiple sites, a battery of unique sequences, and repeatedsynthesis and ligation steps would be required.

c) The inner few bases of the primer could be thiolated and anexonuclease used to produce properly tailed molecules.

The recovery of the re-assorted sequences relies on the identificationof cloning vectors with a reduced repetitive index (RI). The re-assortedencoding sequences can then be recovered by amplification. The productsare re-cloned and expressed. The recovery of cloning vectors withreduced RI can be affected by:

1) The use of vectors only stably maintained when the construct isreduced in complexity.

2) The physical recovery of shortened vectors by physical procedures. Inthis case, the cloning vector would be recovered using standard plasmidisolation procedures and size fractionated on either an agarose gel, orcolumn with a low molecular weight cut off utilizing standardprocedures.

3) The recovery of vectors containing interrupted genes which can beselected when insert size decreases.

4) The use of direct selection techniques with an expression vector andthe appropriate selection.

Encoding sequences (for example, genes) from related organisms maydemonstrate a high degree of homology and encode quite diverse proteinproducts. These types of sequences are particularly useful in thepresent invention as quasi-repeats. However, while the examplesillustrated below demonstrate the reassortment of nearly identicaloriginal encoding sequences (quasi-repeats), this process is not limitedto such nearly identical repeats.

The following example demonstrates a method of the invention. Encodingnucleic acid sequences (quasi-repeats) derived from three (3) uniquespecies are described. Each sequence encodes a protein with a distinctset of properties. Each of the sequences differs by a single or a fewbase pairs at a unique position in the sequence. The quasi-repeatedsequences are separately or collectively amplified and ligated intorandom assemblies such that all possible permutations and combinationsare available in the population of ligated molecules. The number ofquasi-repeat units can be controlled by the assembly conditions. Theaverage number of quasi-repeated units in a construct is defined as therepetitive index (RI).

Once formed, the constructs may, or may not be size fractionated on anagarose gel according to published protocols, inserted into a cloningvector, and transfected into an appropriate host cell. The cells arethen propagated and “reductive reassortment” is effected. The rate ofthe reductive reassortment process may be stimulated by the introductionof DNA damage if desired. Whether the reduction in RI is mediated bydeletion formation between repeated sequences by an “intra-molecular”mechanism, or mediated by recombination-like events through“inter-molecular” mechanisms is immaterial. The end result is areassortment of the molecules into all possible combinations.

Optionally, the method comprises the additional step of screening thelibrary members of the shuffled pool to identify individual shuffledlibrary members having the ability to bind or otherwise interact, orcatalyze a particular reaction (e.g., such as catalytic domain of anenzyme) with a predetermined macromolecule, such as for example aproteinaceous receptor, an oligosaccharide, viron, or otherpredetermined compound or structure.

The polypeptides that are identified from such libraries can be used fortherapeutic, diagnostic, research and related purposes (e.g., catalysts,solutes for increasing osmolarity of an aqueous solution, and the like),and/or can be subjected to one or more additional cycles of shufflingand/or selection.

In another aspect, it is envisioned that prior to or duringrecombination or reassortment, polynucleotides generated by the methodof the invention can be subjected to agents or processes which promotethe introduction of mutations into the original polynucleotides. Theintroduction of such mutations would increase the diversity of resultinghybrid polynucleotides and polypeptides encoded therefrom. The agents orprocesses which promote mutagenesis can include, but are not limited to:(+)-CC-1065, or a synthetic analog such as (+)-CC-1065-(N3-Adenine (SeeSun and Hurley, (1992); an N-acelylated or deacetylated4′-fluro-4-aminobiphenyl adduct capable of inhibiting DNA synthesis(See, for example, van de Poll et al. (1992)); or a N-acetylated ordeacetylated 4-aminobiphenyl adduct capable of inhibiting DNA synthesis(See also, van de Poll et al. (1992), pp. 751-758); trivalent chromium,a trivalent chromium salt, a polycyclic aromatic hydrocarbon (PAH) DNAadduct capable of inhibiting DNA replication, such as7-bromomethyl-benz[a]anthracene (“BMA”),tris(2,3-dibromopropyl)phosphate (“Tris-BP”),1,2-dibromo-3-chloropropane (“DBCP”), 2-bromoacrolein (2BA),benzo[a]pyrene-7,8-dihydrodiol-9-10-epoxide (“BPDE”), a platinum(II)halogen salt, N-hydroxy-2-amino-3-methylimidazo[4,5-f]-quinoline(“N-hydroxy-IQ”), andN-hydroxy-2-amino-1-methyl-6-phenylimidazo[4,5-f]-pyridine(“N-hydroxy-PhIP”). Especially preferred means for slowing or haltingPCR amplification consist of UV light (+)-CC-1065 and(+)-CC-1065-(N3-Adenine). Particularly encompassed means are DNA adductsor polynucleotides comprising the DNA adducts from the polynucleotidesor polynucleotides pool, which can be released or removed by a processincluding heating the solution comprising the polynucleotides prior tofurther processing.

In another aspect the invention is directed to a method of producingrecombinant proteins having biological activity by treating a samplecomprising double-stranded template polynucleotides encoding a wild-typeprotein under conditions according to the invention which provide forthe production of hybrid or re-assorted polynucleotides.

The invention also provides for the use of proprietary codon primers(containing a degenerate N,N,N sequence) to introduce point mutationsinto a polynucleotide, so as to generate a set of progeny polyp eptidesin which a full range of single amino acid substitutions is representedat each amino acid position Gene Site Saturation Mutagenesis™ (GSSM™)).The oligos used are comprised contiguously of a first homologoussequence, a degenerate N,N,N sequence, and preferably but notnecessarily a second homologous sequence. The downstream progenytranslational products from the use of such oligos include all possibleamino acid changes at each amino acid site along the polypeptide,because the degeneracy of the N,N,N sequence includes codons for all 20amino acids.

In one aspect, one such degenerate oligo (comprised of one degenerateN,N,N cassette) is used for subjecting each original codon in a parentalpolynucleotide template to a full range of codon substitutions. Inanother aspect, at least two degenerate N,N,N cassettes are used—eitherin the same oligo or not, for subjecting at least two original codons ina parental polynucleotide template to a full range of codonsubstitutions. Thus, more than one N,N,N sequence can be contained inone oligo to introduce amino acid mutations at more than one site. Thisplurality of N,N,N sequences can be directly contiguous, or separated byone or more additional nucleotide sequence(s). In another aspect, oligosserviceable for introducing additions and deletions can be used eitheralone or in combination with the codons containing an N,N,N sequence, tointroduce any combination or permutation of amino acid additions,deletions, and/or substitutions.

In a particular exemplification, it is possible to simultaneouslymutagenize two or more contiguous amino acid positions using an oligothat contains contiguous N,N,N triplets, i.e. a degenerate (N,N,N)nsequence.

In another aspect, the present invention provides for the use ofdegenerate cassettes having less degeneracy than the N,N,N sequence. Forexample, it may be desirable in some instances to use (e.g. in an oligo)a degenerate triplet sequence comprised of only one N, where said N canbe in the first second or third position of the triplet. Any other basesincluding any combinations and permutations thereof can be used in theremaining two positions of the triplet. Alternatively, it may bedesirable in some instances to use (e.g., in an oligo) a degenerateN,N,N triplet sequence, N,N,G/T, or an N,N, G/C triplet sequence.

It is appreciated, however, that the use of a degenerate triplet (suchas N,N,G/T or an N,N, G/C triplet sequence) as disclosed in the instantinvention is advantageous for several reasons. In one aspect, thisinvention provides a means to systematically and fairly easily generatethe substitution of the full range of possible amino acids (for a totalof 20 amino acids) into each and every amino acid position in apolypeptide. Thus, for a 100 amino acid polypeptide, the inventionprovides a way to systematically and fairly easily generate 2000distinct species (i.e., 20 possible amino acids per position times 100amino acid positions). It is appreciated that there is provided, throughthe use of an oligo containing a degenerate N,N,G/T or an N,N, G/Ctriplet sequence, 32 individual sequences that code for 20 possibleamino acids. Thus, in a reaction vessel in which a parentalpolynucleotide sequence is subjected to saturation mutagenesis using onesuch oligo, there are generated 32 distinct progeny polynucleotidesencoding 20 distinct polypeptides. In contrast, the use of anon-degenerate oligo in site-directed mutagenesis leads to only oneprogeny polypeptide product per reaction vessel.

This invention also provides for the use of nondegenerate oligos, whichcan optionally be used in combination with degenerate primers disclosed.It is appreciated that in some situations, it is advantageous to usenondegenerate oligos to generate specific point mutations in a workingpolynucleotide. This provides a means to generate specific silent pointmutations, point mutations leading to corresponding amino acid changes,and point mutations that cause the generation of stop codons and thecorresponding expression of polypeptide fragments.

Thus, in a preferred embodiment of this invention, each saturationmutagenesis reaction vessel contains polynucleotides encoding at least20 progeny polypeptide molecules such that all 20 amino acids arerepresented at the one specific amino acid position corresponding to thecodon position mutagenized in the parental polynucleotide. The 32-folddegenerate progeny polypeptides generated from each saturationmutagenesis reaction vessel can be subjected to clonal amplification(e.g., cloned into a suitable E. coli host using an expression vector)and subjected to expression screening. When an individual progenypolypeptide is identified by screening to display a favorable change inproperty (when compared to the parental polypeptide), it can besequenced to identify the correspondingly favorable amino acidsubstitution contained therein.

It is appreciated that upon mutagenizing each and every amino acidposition in a parental polypeptide using saturation mutagenesis asdisclosed herein, favorable amino acid changes may be identified at morethan one amino acid position. One or more new progeny molecules can begenerated that contain a combination of all or part of these favorableamino acid substitutions. For example, if 2 specific favorable aminoacid changes are identified in each of 3 amino acid positions in apolypeptide, the permutations include 3 possibilities at each position(no change from the original amino acid, and each of two favorablechanges) and 3 positions. Thus, there are 3×3×3 or 27 totalpossibilities, including 7 that were previously examined—6 single pointmutations (i.e., 2 at each of three positions) and no change at anyposition.

In yet another aspect, site-saturation mutagenesis can be used togetherwith shuffling, chimerization, recombination and other mutagenizingprocesses, along with screening. This invention provides for the use ofany mutagenizing process(es), including saturation mutagenesis, in aniterative manner. In one exemplification, the iterative use of anymutagenizing process(es) is used in combination with screening.

Thus, in a non-limiting exemplification, this invention provides for theuse of saturation mutagenesis in combination with additionalmutagenization processes, such as process where two or more relatedpolynucleotides are introduced into a suitable host cell such that ahybrid polynucleotide is generated by recombination and reductivereassortment.

In addition to performing mutagenesis along the entire sequence of agene, the instant invention provides that mutagenesis can be use toreplace each of any number of bases in a polynucleotide sequence,wherein the number of bases to be mutagenized is preferably everyinteger from 15 to 100,000. Thus, instead of mutagenizing every positionalong a molecule, one can subject every or a discrete number of bases(preferably a subset totaling from 15 to 100,000) to mutagenesis.Preferably, a separate nucleotide is used for mutagenizing each positionor group of positions along a polynucleotide sequence. A group of 3positions to be mutagenized may be a codon. The mutations are preferablyintroduced using a mutagenic primer, containing a heterologous cassette,also referred to as a mutagenic cassette. Preferred cassettes can havefrom 1 to 500 bases. Each nucleotide position in such heterologouscassettes be N, A, C, G, T, A/C, A/G, A/T, C/G, C/T, G/T, C/G/T, A/G/T,A/C/T, A/C/G, or E, where E is any base that is not A, C, G, or T (E canbe referred to as a designer oligo).

In a general sense, saturation mutagenesis is comprised of mutagenizinga complete set of mutagenic cassettes (wherein each cassette ispreferably about 1-500 bases in length) in defined polynucleotidesequence to be mutagenized (wherein the sequence to be mutagenized ispreferably from about 15 to 100,000 bases in length). Thus, a group ofmutations (ranging from 1 to 100 mutations) is introduced into eachcassette to be mutagenized. A grouping of mutations to be introducedinto one cassette can be different or the same from a second grouping ofmutations to be introduced into a second cassette during the applicationof one round of saturation mutagenesis. Such groupings are exemplifiedby deletions, additions, groupings of particular codons, and groupingsof particular nucleotide cassettes.

Defined sequences to be mutagenized include a whole gene, pathway, cDNA,an entire open reading frame (ORF), and entire promoter, enhancer,repressor/transactivator, origin of replication, intron, operator, orany polynucleotide functional group. Generally, a “defined sequences”for this purpose may be any polynucleotide that a 15 base-polynucleotidesequence, and polynucleotide sequences of lengths between 15 bases and15,000 bases (this invention specifically names every integer inbetween). Considerations in choosing groupings of codons include typesof amino acids encoded by a degenerate mutagenic cassette.

In a particularly preferred exemplification a grouping of mutations thatcan be introduced into a mutagenic cassette, this invention specificallyprovides for degenerate codon substitutions (using degenerate oligos)that code for 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,18, 19, and 20 amino acids at each position, and a library ofpolypeptides encoded thereby.

One aspect of the invention is an isolated nucleic acid comprising oneof the sequences of SEQ ID NO:1 nucleic acid sequences, and sequencessubstantially identical thereto, the sequences complementary thereto, ora fragment comprising at least 10, 15, 20, 25, 30, 35, 40, 50, 75, 100,150, 200, 300, 400, or 500 consecutive bases of one of the sequences ofa SEQ ID NO:1 nucleic acid sequence (or the sequences complementarythereto). The isolated, nucleic acids may comprise DNA, including cDNA,genomic DNA, and synthetic DNA. The DNA may be double-stranded orsingle-stranded, and if single stranded may be the coding strand ornon-coding (anti-sense) strand. Alternatively, the isolated nucleicacids may comprise RNA.

As discussed in more detail below, the isolated nucleic acids of one ofthe SEQ ID NO:1 nucleic acid sequences, and sequences substantiallyidentical thereto, may be used to prepare one of the polypeptides of aSEQ ID NO:2 amino acid sequence, and sequences substantially identicalthereto, or fragments comprising at least 5, 10, 15, 20, 25, 30, 35, 40,50, 75, 100, or 150 consecutive amino acids of one of the polypeptidesof SEQ ID NO:2 amino acid sequences, and sequences substantiallyidentical thereto.

Accordingly, another aspect of the invention is an isolated nucleic acidwhich encodes one of the polypeptides of SEQ ID NO:2 amino acidsequences, and sequences substantially identical thereto, or fragmentscomprising at least 5, 10, 15, 20, 25, 30, 35, 40, 50, 75, 100, or 150consecutive amino acids of one of the polypeptides of the SEQ ID NO:2amino acid sequences. The coding sequences of these nucleic acids may beidentical to one of the coding sequences of one of the nucleic acids ofSEQ ID NO:1 nucleic acid sequences, or a fragment thereof or may bedifferent coding sequences which encode one of the polypeptides of SEQID NO:2 amino acid sequences, sequences substantially identical thereto,and fragments having at least 5, 10, 15, 20, 25, 30, 35, 40, 50, 75,100, or 150 consecutive amino acids of one of the polypeptides of SEQ IDNO:2 amino acid sequences, as a result of the redundancy or degeneracyof the genetic code. The genetic code is well known to those of skill inthe art and can be obtained, for example, on page 214 of B. Lewin, GenesVI, Oxford University Press, 1997, the disclosure of which isincorporated herein by reference.

The isolated nucleic acid which encodes one of the polypeptides of SEQID NO:2 amino acid sequences, and sequences substantially identicalthereto, may include, but is not limited to: only the coding sequence ofone of SEQ ID NO:1 nucleic acid sequences, and sequences substantiallyidentical thereto, and additional coding sequences, such as leadersequences or proprotein sequences and non-coding sequences, such asintrons or non-coding sequences 5′ and/or 3′ of the coding sequence.Thus, as used herein, the term “polynucleotide encoding a polypeptide”encompasses a polynucleotide which includes only the coding sequence forthe polypeptide as well as a polynucleotide which includes additionalcoding and/or non-coding sequence.

Alternatively, the nucleic acid sequences of SEQ ID NO:1 nucleic acidsequences, and sequences substantially identical thereto, may bemutagenized using conventional techniques, such as site directedmutagenesis, or other techniques familiar to those skilled in the art,to introduce silent changes into the polynucleotides of SEQ ID NO:1nucleic acid sequences, and sequences substantially identical thereto.As used herein, “silent changes” include, for example, changes which donot alter the amino acid sequence encoded by the polynucleotide. Suchchanges may be desirable in order to increase the level of thepolypeptide produced by host cells containing a vector encoding thepolypeptide by introducing codons or codon pairs which occur frequentlyin the host organism.

The invention also relates to polynucleotides which have nucleotidechanges which result in amino acid substitutions, additions, deletions,fusions and truncations in the polypeptides of SEQ ID NO:2 amino acidsequences, and sequences substantially identical thereto. Suchnucleotide changes may be introduced using techniques such as sitedirected mutagenesis, random chemical mutagenesis, exonuclease IIIdeletion, and other recombinant DNA techniques. Alternatively, suchnucleotide changes may be naturally occurring allelic variants which areisolated by identifying nucleic acids which specifically hybridize toprobes comprising at least 10, 15, 20, 25, 30, 35, 40, 50, 75, 100, 150,200, 300, 400, or 500 consecutive bases of one of the sequences of SEQID NO:1 nucleic acid sequences, and sequences substantially identicalthereto (or the sequences complementary thereto) under conditions ofhigh, moderate, or low stringency as provided herein.

The isolated nucleic acids of SEQ ID NO:1 nucleic acid sequences, andsequences substantially identical thereto, the sequences complementarythereto, or a fragment comprising at least 10, 15, 20, 25, 30, 35, 40,50, 75, 100, 150, 200, 300, 400, or 500 consecutive bases of one of thesequences of SEQ ID NO:1 nucleic acid sequences, and sequencessubstantially identical thereto, or the sequences complementary theretomay also be used as probes to determine whether a biological sample,such as a soil sample, contains an organism having a nucleic acidsequence of the invention or an organism from which the nucleic acid wasobtained. In such procedures, a biological sample potentially harboringthe organism from which the nucleic acid was isolated is obtained andnucleic acids are obtained from the sample. The nucleic acids arecontacted with the probe under conditions which permit the probe tospecifically hybridize to any complementary sequences from which arepresent therein.

Where necessary, conditions which permit the probe to specificallyhybridize to complementary sequences may be determined by placing theprobe in contact with complementary sequences from samples known tocontain the complementary sequence as well as control sequences which donot contain the complementary sequence. Hybridization conditions, suchas the salt concentration of the hybridization buffer, the formamideconcentration of the hybridization buffer, or the hybridizationtemperature, may be varied to identify conditions which allow the probeto hybridize specifically to complementary nucleic acids.

If the sample contains the organism from which the nucleic acid wasisolated, specific hybridization of the probe is then detected.Hybridization may be detected by labeling the probe with a detectableagent such as a radioactive isotope, a fluorescent dye or an enzymecapable of catalyzing the formation of a detectable product.

Many methods for using the labeled probes to detect the presence ofcomplementary nucleic acids in a sample are familiar to those skilled inthe art. These include Southern Blots, Northern Blots, colonyhybridization procedures, and dot blots. Protocols for each of theseprocedures are provided in Ausubel et al. Current Protocols in MolecularBiology, John Wiley 503 Sons, Inc. (1997) and Sambrook et al., MolecularCloning: A Laboratory Manual 2nd Ed., Cold Spring Harbor LaboratoryPress (1989), the entire disclosures of which are incorporated herein byreference.

Alternatively, more than one probe (at least one of which is capable ofspecifically hybridizing to any complementary sequences which arepresent in the nucleic acid sample), may be used in an amplificationreaction to determine whether the sample contains an organism containinga nucleic acid sequence of the invention (e.g., an organism from whichthe nucleic acid was isolated). Typically, the probes compriseoligonucleotides. In one embodiment, the amplification reaction maycomprise a PCR reaction. PCR protocols are described in Ausubel andSambrook, supra. Alternatively, the amplification may comprise a ligasechain reaction, 3SR, or strand displacement reaction. (See Barany, F.,“The Ligase Chain Reaction in a PCR World”, PCR Methods and Applications1:5-16, 1991; E. Fahy et al., “Self-sustained Sequence Replication(3SR): An Isothermal Transcription-based Amplification SystemAlternative to PCR”, PCR Methods and Applications 1:25-33, 1991; andWalker G. T. et al., “Strand Displacement Amplification-an Isothermal invitro DNA Amplification Technique”, Nucleic Acid Research 20:1691-1696,1992, the disclosures of which are incorporated herein by reference intheir entireties). In such procedures, the nucleic acids in the sampleare contacted with the probes, the amplification reaction is performed,and any resulting amplification product is detected. The amplificationproduct may be detected by performing gel electrophoresis on thereaction products and staining the gel with an interculator such asethidium bromide. Alternatively, one or more of the probes may belabeled with a radioactive isotope and the presence of a radioactiveamplification product may be detected by autoradiography after gelelectrophoresis.

Probes derived from sequences near the ends of the sequences of SEQ IDNO:1 nucleic acid sequences, and sequences substantially identicalthereto, may also be used in chromosome walking procedures to identifyclones containing genomic sequences located adjacent to the sequences ofSEQ ID NO:1 nucleic acid sequences, and sequences substantiallyidentical thereto. Such methods allow the isolation of genes whichencode additional proteins from the host organism.

The isolated nucleic acids of SEQ ID NO:1 nucleic acid sequences, andsequences substantially identical thereto, the sequences complementarythereto, or a fragment comprising at least 10, 15, 20, 25, 30, 35, 40,50, 75, 100, 150, 200, 300, 400, or 500 consecutive bases of one of thesequences of SEQ ID NO:1 nucleic acid sequences, and sequencessubstantially identical thereto, or the sequences complementary theretomay be used as probes to identify and isolate related nucleic acids. Insome embodiments, the related nucleic acids may be cDNAs or genomic DNAsfrom organisms other than the one from which the nucleic acid wasisolated. For example, the other organisms may be related organisms. Insuch procedures, a nucleic acid sample is contacted with the probe underconditions which permit the probe to specifically hybridize to relatedsequences. Hybridization of the probe to nucleic acids from the relatedorganism is then detected using any of the methods described above.

In nucleic acid hybridization reactions, the conditions used to achievea particular level of stringency will vary, depending on the nature ofthe nucleic acids being hybridized. For example, the length, degree ofcomplementarity, nucleotide sequence composition (e.g., GC v. ATcontent), and nucleic acid type (e.g., RNA v. DNA) of the hybridizingregions of the nucleic acids can be considered in selectinghybridization conditions. An additional consideration is whether one ofthe nucleic acids is immobilized, for example, on a filter.

Hybridization may be carried out under conditions of low stringency,moderate stringency or high stringency. As an example of nucleic acidhybridization, a polymer membrane containing immobilized denaturednucleic acids is first prehybridized for 30 minutes at 45° C. in asolution consisting of 0.9 M NaCl, 50 mM NaH2PO4, pH 7.0, 5.0 mMNa2EDTA, 0.5% SDS, 10× Denhardt's, and 0.5 mg/ml polyriboadenylic acid.Approximately 2×107 cpm (specific activity 4-9×108 cpm/ug) of 32Pend-labeled oligonucleotide probe are then added to the solution. After12-16 hours of incubation, the membrane is washed for 30 minutes at roomtemperature in 1× SET (150 mM NaCl, 20 mM Tris hydrochloride, pH 7.8, 1mM Na2EDTA) containing 0.5% SDS, followed by a 30 minute wash in fresh1× SET at Tm-10° C. for the oligonucleotide probe. The membrane is thenexposed to auto-radiographic film for detection of hybridizationsignals.

By varying the stringency of the hybridization conditions used toidentify nucleic acids, such as cDNAs or genomic DNAs, which hybridizeto the detectable probe, nucleic acids having different levels ofhomology to the probe can be identified and isolated. Stringency may bevaried by conducting the hybridization at varying temperatures below themelting temperatures of the probes. The melting temperature, Tm, is thetemperature (under defined ionic strength and pH) at which 50% of thetarget sequence hybridizes to a perfectly complementary probe. Verystringent conditions are selected to be equal to or about 5° C. lowerthan the Tm for a particular probe. The melting temperature of the probemay be calculated using the following formulas:

For probes between 14 and 70 nucleotides in length the meltingtemperature (Tm) is calculated using the formula: Tm=81.5+16.6(log[Na+])+0.41(fraction G+C)−(600/N) where N is the length of the probe.

If the hybridization is carried out in a solution containing formamide,the melting temperature may be calculated using the equation:Tm=81.5+16.6(log [Na+])+0.41 (fraction G+C)−(0.63% formamide)−(600/N)where N is the length of the probe.

Prehybridization may be carried out in 6×SSC, 5× Denhardt's reagent,0.5% SDS, 100 μg denatured fragmented salmon sperm DNA or 6×SSC, 5×Denhardt's reagent, 0.5% SDS, 100 μg denatured fragmented salmon spermDNA, 50% formamide. The formulas for SSC and Denhardt's solutions arelisted in Sambrook et al., supra.

Hybridization is conducted by adding the detectable probe to theprehybridization solutions listed above. Where the probe comprisesdouble stranded DNA, it is denatured before addition to thehybridization solution. The filter is contacted with the hybridizationsolution for a sufficient period of time to allow the probe to hybridizeto cDNAs or genomic DNAs containing sequences complementary thereto orhomologous thereto. For probes over 200 nucleotides in length, thehybridization may be carried out at 15-25° C. below the Tm. For shorterprobes, such as oligonucleotide probes, the hybridization may beconducted at 5-10° C. below the Tm. Typically, for hybridizations in6×SSC, the hybridization is conducted at approximately 68° C. Usually,for hybridizations in 50% formamide containing solutions, thehybridization is conducted at approximately 42° C.

All of the foregoing hybridizations would be considered to be underconditions of high stringency.

Following hybridization, the filter is washed to remove anynon-specifically bound detectable probe. The stringency used to wash thefilters can also be varied depending on the nature of the nucleic acidsbeing hybridized, the length of the nucleic acids being hybridized, thedegree of complementarity, the nucleotide sequence composition (e.g., GCv. AT content), and the nucleic acid type (e.g., RNA v. DNA). Examplesof progressively higher stringency condition washes are as follows:2×SSC, 0.1% SDS at room temperature for 15 minutes (low stringency);0.1×SSC, 0.5% SDS at room temperature for 30 minutes to 1 hour (moderatestringency); 0.1×SSC, 0.5% SDS for 15 to 30 minutes at between thehybridization temperature and 68° C. (high stringency); and 0.15M NaClfor 15 minutes at 72° C. (very high stringency). A final low stringencywash can be conducted in 0.1×SSC at room temperature. The examples aboveare merely illustrative of one set of conditions that can be used towash filters. One of skill in the art would know that there are numerousrecipes for different stringency washes. Some other examples are givenbelow.

Nucleic acids which have hybridized to the probe are identified byautoradiography or other conventional techniques.

The above procedure may be modified to identify nucleic acids havingdecreasing levels of homology to the probe sequence. For example, toobtain nucleic acids of decreasing homology to the detectable probe,less stringent conditions may be used. For example, the hybridizationtemperature may be decreased in increments of 5° C. from 68° C. to 42°C. in a hybridization buffer having a Na+ concentration of approximately1M. Following hybridization, the filter may be washed with 2×SSC, 0.5%SDS at the temperature of hybridization. These conditions are consideredto be “moderate” conditions above 50° C. and “low” conditions below 50°C. A specific example of “moderate” hybridization conditions is when theabove hybridization is conducted at 55° C. A specific example of “lowstringency” hybridization conditions is when the above hybridization isconducted at 45° C.

Alternatively, the hybridization may be carried out in buffers, such as6×SSC, containing formamide at a temperature of 42° C. In this case, theconcentration of formamide in the hybridization buffer may be reduced in5% increments from 50% to 0% to identify clones having decreasing levelsof homology to the probe. Following hybridization, the filter may bewashed with 6×SSC, 0.5% SDS at 50° C. These conditions are considered tobe “moderate” conditions above 25% formamide and “low” conditions below25% formamide. A specific example of “moderate” hybridization conditionsis when the above hybridization is conducted at 30% formamide. Aspecific example of “low stringency” hybridization conditions is whenthe above hybridization is conducted at 10% formamide.

For example, the preceding methods may be used to isolate nucleic acidshaving a sequence with at least about 97%, at least 95%, at least 90%,at least 85%, at least 80%, at least 70%, at least 65%, at least 60%, atleast 55%, or at least 50% homology to a nucleic acid sequence selectedfrom the group consisting of one of the sequences of SEQ ID NO:1 nucleicacid sequences, and sequences substantially identical thereto, orfragments comprising at least about 10, 15, 20, 25, 30, 35, 40, 50, 75,100, 150, 200, 300, 400, or 500 consecutive bases thereof, and thesequences complementary thereto. Homology may be measured using thealignment algorithm. For example, the homologous polynucleotides mayhave a coding sequence which is a naturally occurring allelic variant ofone of the coding sequences described herein. Such allelic variants mayhave a substitution, deletion or addition of one or more nucleotideswhen compared to the nucleic acids of SEQ ID NO:1 nucleic acid sequencesor the sequences complementary thereto.

Additionally, the above procedures may be used to isolate nucleic acidswhich encode polypeptides having at least about 99%, 95%, at least 90%,at least 85%, at least 80%, at least 75%, at least 70%, at least 65%, atleast 60%, at least 55%, or at least 50% homology to a polypeptidehaving the sequence of one of SEQ ID NO:2 amino acid sequences, andsequences substantially identical thereto, or fragments comprising atleast 5, 10, 15, 20, 25, 30, 35, 40, 50, 75, 100, or 150 consecutiveamino acids thereof as determined using a sequence alignment algorithm(e.g., such as the FASTA version 3.0t78 algorithm with the defaultparameters).

Another aspect of the invention is an isolated or purified polypeptidecomprising the sequence of one of SEQ ID NO:1 nucleic acid sequences,and sequences substantially identical thereto, or fragments comprisingat least about 5, 10, 15, 20, 25, 30, 35, 40, 50, 75, 100, or 150consecutive amino acids thereof. As discussed above, such polypeptidesmay be obtained by inserting a nucleic acid encoding the polypeptideinto a vector such that the coding sequence is operably linked to asequence capable of driving the expression of the encoded polypeptide ina suitable host cell. For example, the expression vector may comprise apromoter, a ribosome binding site for translation initiation and atranscription terminator. The vector may also include appropriatesequences for amplifying expression.

Promoters suitable for expressing the polypeptide or fragment thereof inbacteria include the E. coli lac or trp promoters, the lacI promoter,the lacZ promoter, the T3 promoter, the T7 promoter, the gpt promoter,the lambda P_(R) promoter, the lambda P_(L) promoter, promoters fromoperons encoding glycolytic enzymes such as 3-phosphoglycerate kinase(PGK), and the acid phosphatase promoter. Fungal promoters include the ∀factor promoter. Eukaryotic promoters include the CMV immediate earlypromoter, the HSV thymidine kinase promoter, heat shock promoters, theearly and late SV40 promoter, LTRs from retroviruses, and the mousemetallothionein-I promoter. Other promoters known to control expressionof genes in prokaryotic or eukaryotic cells or their viruses may also beused.

Mammalian expression vectors may also comprise an origin of replication,any necessary ribosome binding sites, a polyadenylation site, splicedonor and acceptor sites, transcriptional termination sequences, and 5′flanking nontranscribed sequences. In some embodiments, DNA sequencesderived from the SV40 splice and polyadenylation sites may be used toprovide the required nontranscribed genetic elements.

Vectors for expressing the polypeptide or fragment thereof in eukaryoticcells may also contain enhancers to increase expression levels.Enhancers are cis-acting elements of DNA, usually from about 10 to about300 bp in length that act on a promoter to increase its transcription.Examples include the SV40 enhancer on the late side of the replicationorigin bp 100 to 270, the cytomegalovirus early promoter enhancer, thepolyoma enhancer on the late side of the replication origin, and theadenovirus enhancers.

In addition, the expression vectors typically contain one or moreselectable marker genes to permit selection of host cells containing thevector. Such selectable markers include genes encoding dihydrofolatereductase or genes conferring neomycin resistance for eukaryotic cellculture, genes conferring tetracycline or ampicillin resistance in E.coli, and the S. cerevisiae TRP1 gene.

In some embodiments, the nucleic acid encoding one of the polypeptidesof SEQ ID NO:2 amino acid sequences, and sequences substantiallyidentical thereto, or fragments comprising at least about 5, 10, 15, 20,25, 30, 35, 40, 50, 75, 100, or 150 consecutive amino acids thereof isassembled in appropriate phase with a leader sequence capable ofdirecting secretion of the translated polypeptide or fragment thereof.Optionally, the nucleic acid can encode a fusion polypeptide in whichone of the polypeptides of SEQ ID NO:2 amino acid sequences, andsequences substantially identical thereto, or fragments comprising atleast 5, 10, 15, 20, 25, 30, 35, 40, 50, 75, 100, or 150 consecutiveamino acids thereof is fused to heterologous peptides or polypeptides,such as N-terminal identification peptides which impart desiredcharacteristics, such as increased stability or simplified purification.

The appropriate DNA sequence may be inserted into the vector by avariety of procedures. In general, the DNA sequence is ligated to thedesired position in the vector following digestion of the insert and thevector with appropriate restriction endonucleases. Alternatively, bluntends in both the insert and the vector may be ligated. A variety ofcloning techniques are disclosed in Ausubel et al. Current Protocols inMolecular Biology, John Wiley 503 Sons, Inc. 1997 and Sambrook et al.,Molecular Cloning: A Laboratory Manual 2nd Ed., Cold Spring HarborLaboratory Press (1989), the entire disclosures of which areincorporated herein by reference. Such procedures and others are deemedto be within the scope of those skilled in the art.

The vector may be, for example, in the form of a plasmid, a viralparticle, or a phage. Other vectors include chromosomal, nonchromosomaland synthetic DNA sequences, derivatives of SV40; bacterial plasmids,phage DNA, baculovirus, yeast plasmids, vectors derived fromcombinations of plasmids and phage DNA, viral DNA such as vaccinia,adenovirus, fowl pox virus, and pseudorabies. A variety of cloning andexpression vectors for use with prokaryotic and eukaryotic hosts aredescribed by Sambrook, et al., Molecular Cloning: A Laboratory Manual,2nd Ed., Cold Spring Harbor, N.Y., (1989), the disclosure of which ishereby incorporated by reference.

Particular bacterial vectors which may be used include the commerciallyavailable plasmids comprising genetic elements of the well known cloningvector pBR322 (ATCC 37017), pKK223-3 (Pharmacia Fine Chemicals, Uppsala,Sweden), GEM1 (Promega Biotec, Madison, Wis., USA) pQE70, pQE60, pQE-9(Qiagen), pD10, psiX174 pBLUESCRIPT II KS, pNH8A, pNH16a, pNH18A, pNH46A(Stratagene), ptrc99a, pKK223-3, pKK233-3, pDR540, pRIT5 (Pharmacia),pKK232-8 and pCM7. Particular eukaryotic vectors include pSV2CAT, pOG44,pXT1, pSG (Stratagene) pSVK3, pBPV, pMSG, and pSVL (Pharmacia). However,any other vector may be used as long as it is replicable and viable inthe host cell.

The host cell may be any of the host cells familiar to those skilled inthe art, including prokaryotic cells, eukaryotic cells, mammalian cells,insect cells, or plant cells. As representative examples of appropriatehosts, there may be mentioned: bacterial cells, such as E. coli,Streptomyces, Bacillus subtilis, Salmonella typhimurium and variousspecies within the genera Pseudomonas, Streptomyces, and Staphylococcus,fungal cells, such as yeast, insect cells such as Drosophila S2 andSpodoptera Sf9, animal cells such as CHO, COS or Bowes melanoma, andadenoviruses. The selection of an appropriate host is within theabilities of those skilled in the art.

The vector may be introduced into the host cells using any of a varietyof techniques, including transformation, transfection, transduction,viral infection, gene guns, or Ti-mediated gene transfer. Particularmethods include calcium phosphate transfection, DEAE-Dextran mediatedtransfection, lipofection, or electroporation (Davis, L., Dibner, M.,Battey, I., Basic Methods in Molecular Biology, (1986)).

Where appropriate, the engineered host cells can be cultured inconventional nutrient media modified as appropriate for activatingpromoters, selecting transformants or amplifying the genes of theinvention. Following transformation of a suitable host strain and growthof the host strain to an appropriate cell density, the selected promotermay be induced by appropriate means (e.g., temperature shift or chemicalinduction) and the cells may be cultured for an additional period toallow them to produce the desired polypeptide or fragment thereof.

Cells are typically harvested by centrifugation, disrupted by physicalor chemical means, and the resulting crude extract is retained forfurther purification. Microbial cells employed for expression ofproteins can be disrupted by any convenient method, includingfreeze-thaw cycling, sonication, mechanical disruption, or use of celllysing agents. Such methods are well known to those skilled in the art.The expressed polypeptide or fragment thereof can be recovered andpurified from recombinant cell cultures by methods including ammoniumsulfate or ethanol precipitation, acid extraction, anion or cationexchange chromatography, phosphocellulose chromatography, hydrophobicinteraction chromatography, affinity chromatography, hydroxylapatitechromatography and lectin chromatography. Protein refolding steps can beused, as necessary, in completing configuration of the polypeptide. Ifdesired, high performance liquid chromatography (HPLC) can be employedfor final purification steps.

Various mammalian cell culture systems can also be employed to expressrecombinant protein. Examples of mammalian expression systems includethe COS-7 lines of monkey kidney fibroblasts (described by Gluzman,Cell, 23:175, 1981), and other cell lines capable of expressing proteinsfrom a compatible vector, such as the C127, 3T3, CHO, HeLa and BHK celllines.

The constructs in host cells can be used in a conventional manner toproduce the gene product encoded by the recombinant sequence. Dependingupon the host employed in a recombinant production procedure, thepolypeptides produced by host cells containing the vector may beglycosylated or may be non-glycosylated. Polypeptides of the inventionmay or may not also include an initial methionine amino acid residue.

Alternatively, the polypeptides of SEQ ID NO:2 amino acid sequences, andsequences substantially identical thereto, or fragments comprising atleast 5, 10, 15, 20, 25, 30, 35, 40, 50, 75, 100, or 150 consecutiveamino acids thereof can be synthetically produced by conventionalpeptide synthesizers. In other embodiments, fragments or portions of thepolypeptides may be employed for producing the corresponding full-lengthpolypeptide by peptide synthesis; therefore, the fragments may beemployed as intermediates for producing the full-length polypeptides.

Cell-free translation systems can also be employed to produce one of thepolypeptides of SEQ ID NO:2 amino acid sequences, and sequencessubstantially identical thereto, or fragments comprising at least 5, 10,15, 20, 25, 30, 35, 40, 50, 75, 100, or 150 consecutive amino acidsthereof using mRNAs transcribed from a DNA construct comprising apromoter operably linked to a nucleic acid encoding the polypeptide orfragment thereof. In some embodiments, the DNA construct may belinearized prior to conducting an in vitro transcription reaction. Thetranscribed mRNA is then incubated with an appropriate cell-freetranslation extract, such as a rabbit reticulocyte extract, to producethe desired polypeptide or fragment thereof.

The invention also relates to variants of the polypeptides of SEQ IDNO:2 amino acid sequences, and sequences substantially identicalthereto, or fragments comprising at least 5, 10, 15, 20, 25, 30, 35, 40,50, 75, 100, or 150 consecutive amino acids thereof. The term “variant”includes derivatives or analogs of these polypeptides. In particular,the variants may differ in amino acid sequence from the polypeptides ofSEQ ID NO:2 amino acid sequences, and sequences substantially identicalthereto, by one or more substitutions, additions, deletions, fusions andtruncations, which may be present in any combination.

The variants may be naturally occurring or created in vitro. Inparticular, such variants may be created using genetic engineeringtechniques such as site directed mutagenesis, random chemicalmutagenesis, Exonuclease III deletion procedures, and standard cloningtechniques. Alternatively, such variants, fragments, analogs, orderivatives may be created using chemical synthesis or modificationprocedures.

Other methods of making variants are also familiar to those skilled inthe art. These include procedures in which nucleic acid sequencesobtained from natural isolates are modified to generate nucleic acidswhich encode polypeptides having characteristics which enhance theirvalue in industrial or laboratory applications. In such procedures, alarge number of variant sequences having one or more nucleotidedifferences with respect to the sequence obtained from the naturalisolate are generated and characterized. Typically, these nucleotidedifferences result in amino acid changes with respect to thepolypeptides encoded by the nucleic acids from the natural isolates.

For example, variants may be created using error prone PCR. In errorprone PCR, PCR is performed under conditions where the copying fidelityof the DNA polymerase is low, such that a high rate of point mutationsis obtained along the entire length of the PCR product. Error prone PCRis described in Leung, D. W., et al., Technique, 1:11-15, 1989) andCaldwell, R. C. & Joyce G. F., PCR Methods Applic., 2:28-33, 1992, thedisclosure of which is incorporated herein by reference in its entirety.Briefly, in such procedures, nucleic acids to be mutagenized are mixedwith PCR primers, reaction buffer, MgCl2, MnCl2, Taq polymerase and anappropriate concentration of dNTPs for achieving a high rate of pointmutation along the entire length of the PCR product. For example, thereaction may be performed using 20 fmoles of nucleic acid to bemutagenized, 30 pmole of each PCR primer, a reaction buffer comprising50 mM KCl, 10 mM Tris HCl (pH 8.3) and 0.01% gelatin, 7 mM MgCl2, 0.5 mMMnCl2, 5 units of Taq polymerase, 0.2 mM dGTP, 0.2 mM dATP, 1 mM dCTP,and 1 mM dTTP. PCR may be performed for 30 cycles of 94° C. for 1 min,45° C. for 1 min, and 72° C. for 1 min. However, it will be appreciatedthat these parameters may be varied as appropriate. The mutagenizednucleic acids are cloned into an appropriate vector and the activitiesof the polypeptides encoded by the mutagenized nucleic acids isevaluated.

Variants may also be created using oligonucleotide directed mutagenesisto generate site-specific mutations in any cloned DNA of interest.Oligonucleotide mutagenesis is described in Reidhaar-Olson, J. F. &Sauer, R. T., et al., Science, 241:53-57, 1988, the disclosure of whichis incorporated herein by reference in its entirety. Briefly, in suchprocedures a plurality of double stranded oligonucleotides bearing oneor more mutations to be introduced into the cloned DNA are synthesizedand inserted into the cloned DNA to be mutagenized. Clones containingthe mutagenized DNA are recovered and the activities of the polypeptidesthey encode are assessed.

Another method for generating variants is assembly PCR. Assembly PCRinvolves the assembly of a PCR product from a mixture of small DNAfragments. A large number of different PCR reactions occur in parallelin the same vial, with the products of one reaction priming the productsof another reaction. Assembly PCR is described in U.S. Pat. No.5,965,408, filed Jul. 9, 1996, entitled, “Method of DNA Reassembly byInterrupting Synthesis”, the disclosure of which is incorporated hereinby reference in its entirety.

Still another method of generating variants is sexual PCR mutagenesis.In sexual PCR mutagenesis, forced homologous recombination occursbetween DNA molecules of different but highly related DNA sequence invitro, as a result of random fragmentation of the DNA molecule based onsequence homology, followed by fixation of the crossover by primerextension in a PCR reaction. Sexual PCR mutagenesis is described inStemmer, W. P., PNAS, USA, 91:10747-10751, 1994, the disclosure of whichis incorporated herein by reference. Briefly, in such procedures aplurality of nucleic acids to be recombined are digested with DNAse togenerate fragments having an average size of 50-200 nucleotides.Fragments of the desired average size are purified and resuspended in aPCR mixture. PCR is conducted under conditions which facilitaterecombination between the nucleic acid fragments. For example, PCR maybe performed by resuspending the purified fragments at a concentrationof 10-30 ng/:1 in a solution of 0.2 mM of each dNTP, 2.2 mM MgCl2, 50 mMKCL, 10 mM Tris HCl, pH 9.0, and 0.1% Triton X-100. 2.5 units of Taqpolymerase per 100:1 of reaction mixture is added and PCR is performedusing the following regime: 94° C. for 60 seconds, 94° C. for 30seconds, 50-55° C. for 30 seconds, 72° C. for 30 seconds (30-45 times)and 72° C. for 5 minutes will be appreciated that these parameters maybe varied as appropriate. In some embodiments, oligonucleotides may beincluded in the PCR reactions. In other embodiments, the Klenow fragmentof DNA polymerase I may be used in a first set of PCR reactions and Taqpolymerase may be used in a subsequent set of PCR reactions. Recombinantsequences are isolated and the activities of the polypeptides theyencode are assessed.

Variants may also be created by in vivo mutagenesis. In someembodiments, random mutations in a sequence of interest are generated bypropagating the sequence of interest in a bacterial strain, such as anE. coli strain, which carries mutations in one or more of the DNA repairpathways. Such “mutator” strains have a higher random mutation rate thanthat of a wild-type parent. Propagating the DNA in one of these strainswill eventually generate random mutations within the DNA. Mutatorstrains suitable for use for in vivo mutagenesis are described in PCTPublication No. WO 91/16427, published Oct. 31, 1991, entitled “Methodsfor Phenotype Creation from Multiple Gene Populations” the disclosure ofwhich is incorporated herein by reference in its entirety.

Variants may also be generated using cassette mutagenesis. In cassettemutagenesis a small region of a double stranded DNA molecule is replacedwith a synthetic oligonucleotide “cassette” that differs from the nativesequence. The oligonucleotide often contains completely and/or partiallyrandomized native sequence.

Recursive ensemble mutagenesis may also be used to generate variants.Recursive ensemble mutagenesis is an algorithm for protein engineering(protein mutagenesis) developed to produce diverse populations ofphenotypically related mutants whose members differ in amino acidsequence. This method uses a feedback mechanism to control successiverounds of combinatorial cassette mutagenesis. Recursive ensemblemutagenesis is described in Arkin, A. P. and Youvan, D. C., PNAS, USA,89:7811-7815, 1992, the disclosure of which is incorporated herein byreference in its entirety.

In some embodiments, variants are created using exponential ensemblemutagenesis. Exponential ensemble mutagenesis is a process forgenerating combinatorial libraries with a high percentage of unique andfunctional mutants, wherein small groups of residues are randomized inparallel to identify, at each altered position, amino acids which leadto functional proteins. Exponential ensemble mutagenesis is described inDelegrave, S. and Youvan, D. C., Biotechnology Research, 11:1548-1552,1993, the disclosure of which incorporated herein by reference in itsentirety. Random and site-directed mutagenesis are described in Arnold,F. H., Current Opinion in Biotechnology, 4:450-455, 1993, the disclosureof which is incorporated herein by reference in its entirety.

In some embodiments, the variants are created using shuffling procedureswherein portions of a plurality of nucleic acids which encode distinctpolypeptides are fused together to create chimeric nucleic acidsequences which encode chimeric polypeptides as described in U.S. Pat.No. 5,965,408, filed Jul. 9, 1996, entitled, “Method of DNA Reassemblyby Interrupting Synthesis”, and U.S. Pat. No. 5,939,250, filed May 22,1996, entitled, “Production of Enzymes Having Desired Activities byMutagenesis”, both of which are incorporated herein by reference.

The variants of the polypeptides of SEQ ID NO:2 amino acid sequences maybe variants in which one or more of the amino acid residues of thepolypeptides of the SEQ ID NO:2 amino acid sequences are substitutedwith a conserved or non-conserved amino acid residue (preferably aconserved amino acid residue) and such substituted amino acid residuemay or may not be one encoded by the genetic code.

Conservative substitutions are those that substitute a given amino acidin a polypeptide by another amino acid of like characteristics.Typically seen as conservative substitutions are the followingreplacements: replacements of an aliphatic amino acid such as Alanine,Valine, Leucine and Isoleucine with another aliphatic amino acid;replacement of a Serine with a Threonine or vice versa; replacement ofan acidic residue such as Aspartic acid and Glutamic acid with anotheracidic residue; replacement of a residue bearing an amide group, such asAsparagine and Glutamine, with another residue bearing an amide group;exchange of a basic residue such as Lysine and Arginine with anotherbasic residue; and replacement of an aromatic residue such asPhenylalanine, Tyrosine with another aromatic residue.

Other variants are those in which one or more of the amino acid residuesof the polypeptides of the SEQ ID NO:2 amino acid sequences includes asubstituent group.

Still other variants are those in which the polypeptide is associatedwith another compound, such as a compound to increase the half-life ofthe polypeptide (for example, polyethylene glycol).

Additional variants are those in which additional amino acids are fusedto the polypeptide, such as a leader sequence, a secretory sequence, aproprotein sequence or a sequence which facilitates purification,enrichment, or stabilization of the polypeptide.

In some embodiments, the fragments, derivatives and analogs retain thesame biological function or activity as the polypeptides of SEQ ID NO:2amino acid sequences, and sequences substantially identical thereto. Inother embodiments, the fragment, derivative, or analog includes aproprotein, such that the fragment, derivative, or analog can beactivated by cleavage of the proprotein portion to produce an activepolypeptide.

Another aspect of the invention is polypeptides or fragments thereofwhich have at least about 50%, at least about 55%, at least about 60%,at least about 65%, at least about 70%, at least about 75%, at leastabout 80%, at least about 85%, at least about 90%, at least about 95%,or more than about 95% homology to one of the polypeptides of SEQ IDNO:2 amino acid sequences, and sequences substantially identicalthereto, or a fragment comprising at least 5, 10, 15, 20, 25, 30, 35,40, 50, 75, 100, or 150 consecutive amino acids thereof. Homology may bedetermined using any of the programs described above which aligns thepolypeptides or fragments being compared and determines the extent ofamino acid identity or similarity between them. It will be appreciatedthat amino acid “homology” includes conservative amino acidsubstitutions such as those described above.

The polypeptides or fragments having homology to one of the polypeptidesof SEQ ID NO:2 amino acid sequences, and sequences substantiallyidentical thereto, or a fragment comprising at least about 5, 10, 15,20, 25, 30, 35, 40, 50, 75, 100, or 150 consecutive amino acids thereofmay be obtained by isolating the nucleic acids encoding them using thetechniques described above.

Alternatively, the homologous polypeptides or fragments may be obtainedthrough biochemical enrichment or purification procedures. The sequenceof potentially homologous polypeptides or fragments may be determined byproteolytic digestion, gel electrophoresis and/or microsequencing. Thesequence of the prospective homologous polypeptide or fragment can becompared to one of the polypeptides of SEQ ID NO:2 amino acid sequences,and sequences substantially identical thereto, or a fragment comprisingat least about 5, 10, 15, 20, 25, 30, 35, 40, 50, 75, 100, or 150consecutive amino acids thereof using any of the programs describedabove.

Another aspect of the invention is an assay for identifying fragments orvariants of SEQ ID NO:2 amino acid sequences, and sequencessubstantially identical thereto, which retain the enzymatic function ofthe polypeptides of SEQ ID NO:2 amino acid sequences, and sequencessubstantially identical thereto. For example the fragments or variantsof said polypeptides, may be used to catalyze biochemical reactions,which indicate that the fragment or variant retains the enzymaticactivity of the polypeptides in the SEQ ID NO:2 amino acid sequences.

The assay for determining if fragments of variants retain the enzymaticactivity of the polypeptides of SEQ ID NO:2 amino acid sequences, andsequences substantially identical thereto includes the steps of:contacting the polypeptide fragment or variant with a substrate moleculeunder conditions which allow the polypeptide fragment or variant tofunction, and detecting either a decrease in the level of substrate oran increase in the level of the specific reaction product of thereaction between the polypeptide and substrate.

The polypeptides of SEQ ID NO:2 amino acid sequences, and sequencessubstantially identical thereto or fragments comprising at least 5, 10,15, 20, 25, 30, 35, 40, 50, 75, 100, or 150 consecutive amino acidsthereof may be used in a variety of applications. For example, thepolypeptides or fragments thereof may be used to catalyze biochemicalreactions. In accordance with one aspect of the invention, there isprovided a process for utilizing the polypeptides of SEQ ID NO:2 aminoacid sequences, and sequences substantially identical thereto orpolynucleotides encoding such polypeptides for hydrolyzing glycosidiclinkages. In such procedures, a substance containing a glycosidiclinkage (e.g., a starch) is contacted with one of the polypeptides ofSEQ ID NO:2 amino acid sequences, or sequences substantially identicalthereto under conditions which facilitate the hydrolysis of theglycosidic linkage.

The polypeptides of SEQ ID NO:2 amino acid sequences, and sequencessubstantially identical thereto or fragments comprising at least 5, 10,15, 20, 25, 30, 35, 40, 50, 75, 100, or 150 consecutive amino acidsthereof, may also be used in the liquefaction and saccharification ofstarch. Using the polypeptides or fragments thereof of this invention,liquefaction may be carried out at a lower pH than with previousenzymes. In one embodiment, liquefaction is performed at a pH of 4.5.Additionally, the polypeptides or fragments thereof of this inventionare less calcium dependent than enzymes previously used in theseprocesses. In liquefaction amylases are used to hydrolyze starch. In apreferred embodiment, the polypeptides or fragments thereof of thisinvention are thermostable at 90-95° C.

The polypeptides of SEQ ID NO:2 amino acid sequences, and sequencessubstantially identical thereto or fragments comprising at least 5, 10,15, 20, 25, 30, 35, 40, 50, 75, 100, or 150 consecutive amino acidsthereof, may also be used to generate antibodies which bind specificallyto the polypeptides or fragments. The resulting antibodies may be usedin immunoaffinity chromatography procedures to isolate or purify thepolypeptide or to determine whether the polypeptide is present in abiological sample. In such procedures, a protein preparation, such as anextract, or a biological sample is contacted with an antibody capable ofspecifically binding to one of the polypeptides of SEQ ID NO:2 aminoacid sequences, and sequences substantially identical thereto, orfragments comprising at least 5, 10, 15, 20, 25, 30, 35, 40, 50, 75,100, or 150 consecutive amino acids thereof.

In immunoaffinity procedures, the antibody is attached to a solidsupport, such as a bead or other column matrix. The protein preparationis placed in contact with the antibody under conditions in which theantibody specifically binds to one of the polypeptides of SEQ ID NO:2amino acid sequences, and sequences substantially identical thereto, orfragment thereof. After a wash to remove non-specifically boundproteins, the specifically bound polypeptides are eluted.

The ability of proteins in a biological sample to bind to the antibodymay be determined using any of a variety of procedures familiar to thoseskilled in the art. For example, binding may be determined by labelingthe antibody with a detectable label such as a fluorescent agent, anenzymatic label, or a radioisotope. Alternatively, binding of theantibody to the sample may be detected using a secondary antibody havingsuch a detectable label thereon. Particular assays include ELISA assays,sandwich assays, radioimmunoassays, and Western Blots.

Polyclonal antibodies generated against the polypeptides of SEQ ID NO:2amino acid sequences, and sequences substantially identical thereto, orfragments comprising at least 5, 10, 15, 20, 25, 30, 35, 40, 50, 75,100, or 150 consecutive amino acids thereof can be obtained by directinjection of the polypeptides into an animal or by administering thepolypeptides to an animal, for example, a nonhuman. The antibody soobtained will then bind the polypeptide itself In this manner, even asequence encoding only a fragment of the polypeptide can be used togenerate antibodies which may bind to the whole native polypeptide. Suchantibodies can then be used to isolate the polypeptide from cellsexpressing that polypeptide.

For preparation of monoclonal antibodies, any technique which providesantibodies produced by continuous cell line cultures can be used.Examples include the hybridoma technique (Kohler and Milstein, Nature,256:495-497, 1975, the disclosure of which is incorporated herein byreference), the trioma technique, the human B-cell hybridoma technique(Kozbor et al., Immunology Today 4:72, 1983, the disclosure of which isincorporated herein by reference), and the EBV-hybridoma technique(Cole, et al., 1985, in Monoclonal Antibodies and Cancer Therapy, AlanR. Liss, Inc., pp. 77-96, the disclosure of which is incorporated hereinby reference).

Techniques described for the production of single chain antibodies (U.S.Pat. No. 4,946,778, the disclosure of which is incorporated herein byreference) can be adapted to produce single chain antibodies to thepolypeptides of SEQ ID NO:2 amino acid sequences, and sequencessubstantially identical thereto, or fragments comprising at least 5, 10,15, 20, 25, 30, 35, 40, 50, 75, 100, or 150 consecutive amino acidsthereof. Alternatively, transgenic mice may be used to express humanizedantibodies to these polypeptides or fragments thereof.

Antibodies generated against the polypeptides of SEQ ID NO:2 amino acidsequences, and sequences substantially identical thereto, or fragmentscomprising at least 5, 10, 15, 20, 25, 30, 35, 40, 50, 75, 100, or 150consecutive amino acids thereof may be used in screening for similarpolypeptides from other organisms and samples. In such techniques,polypeptides from the organism are contacted with the antibody and thosepolypeptides which specifically bind the antibody are detected. Any ofthe procedures described above may be used to detect antibody binding.One such screening assay is described in “Methods for MeasuringCellulase Activities”, Methods in Enzymology, Vol 160, pp. 87-116, whichis hereby incorporated by reference in its entirety.

As used herein the term “nucleic acid sequence as set forth in SEQ IDNO.: 1” encompasses the nucleotide sequences of SEQ ID NO:1 nucleic acidsequences, and sequences substantially identical thereto, as well assequences homologous to SEQ ID NO:1 nucleic acid sequences, andfragments thereof and sequences complementary to all of the precedingsequences. The fragments include portions of SEQ ID NO.: 1, comprisingat least 10, 15, 20, 25, 30, 35, 40, 50, 75, 100, 150, 200, 300, 400, or500 consecutive nucleotides of SEQ ID NO:1 nucleic acid sequences, andsequences substantially identical thereto. Homologous sequences andfragments of SEQ ID NO:1 nucleic acid sequences, and sequencessubstantially identical thereto, refer to a sequence having at least99%, 98%, 97%, 96%, 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55% or 50%homology to these sequences. Homology may be determined using any of thecomputer programs and parameters described herein, including FASTAversion 3.0t78 with the default parameters. Homologous sequences alsoinclude RNA sequences in which uridines replace the thymines in thenucleic acid sequences as set forth in the SEQ ID NO:1 nucleic acidsequences. The homologous sequences may be obtained using any of theprocedures described herein or may result from the correction of asequencing error. It will be appreciated that the nucleic acid sequencesas set forth in SEQ ID NO:1 nucleic acid sequences, and sequencessubstantially identical thereto, can be represented in the traditionalsingle character format (See the inside back cover of Stryer, Lubert.Biochemistry, 3rd Ed., W.H Freeman & Co., New York.) or in any otherformat which records the identity of the nucleotides in a sequence.

As used herein the term “a polypeptide sequence as set forth in SEQ IDNO:2” encompasses the polypeptide sequence of SEQ ID NO:2 amino acidsequences, and sequences substantially identical thereto, which areencoded by a sequence as set forth in SEQ ID NO:2, polypeptide sequenceshomologous to the polypeptides of SEQ ID NO:2 amino acid sequences, andsequences substantially identical thereto, or fragments of any of thepreceding sequences. Homologous polypeptide sequences refer to apolypeptide sequence having at least 99%, 98%, 97%, 96%, 95%, 90%, 85%,80%, 75%, 70%, 65%, 60%, 55% or 50% homology to one of the polypeptidesequences of the SEQ ID NO:2 amino acid sequences. Homology may bedetermined using any of the computer programs and parameters describedherein, including FASTA version 3.0t78 with the default parameters orwith any modified parameters. The homologous sequences may be obtainedusing any of the procedures described herein or may result from thecorrection of a sequencing error. The polypeptide fragments comprise atleast 5, 10, 15, 20, 25, 30, 35, 40, 50, 75, 100, or 150 consecutiveamino acids of the polypeptides of SEQ ID NO:2 amino acid sequences, andsequences substantially identical thereto. It will be appreciated thatthe polypeptide codes as set forth in SEQ ID NO:2 amino acid sequences,and sequences substantially identical thereto, can be represented in thetraditional single character format or three letter format (See theinside back cover of Stryer, Lubert. Biochemistry, 3rd Ed., W.H Freeman& Co., New York.) or in any other format which relates the identity ofthe polypeptides in a sequence.

It will be appreciated by those skilled in the art that a nucleic acidsequence as set forth in SEQ ID No.: 1 and a polypeptide sequence as setforth in SEQ ID No.: 2 can be stored, recorded, and manipulated on anymedium which can be read and accessed by a computer. As used herein, thewords “recorded” and “stored” refer to a process for storing informationon a computer medium. A skilled artisan can readily adopt any of thepresently known methods for recording information on a computer readablemedium to generate manufactures comprising one or more of the nucleicacid sequences as set forth in SEQ ID NO:1 nucleic acid sequences, andsequences substantially identical thereto, one or more of thepolypeptide sequences as set forth in SEQ ID NO:2 amino acid sequences,and sequences substantially identical thereto. Another aspect of theinvention is a computer readable medium having recorded thereon at least2, 5, 10, 15, or 20 nucleic acid sequences as set forth in SEQ ID NO:1nucleic acid sequences, and sequences substantially identical thereto.

Another aspect of the invention is a computer readable medium havingrecorded thereon one or more of the nucleic acid sequences as set forthin SEQ ID NO:1 nucleic acid sequences, and sequences substantiallyidentical thereto. Another aspect of the invention is a computerreadable medium having recorded thereon one or more of the polypeptidesequences as set forth in SEQ ID NO:2 amino acid sequences, andsequences substantially identical thereto. Another aspect of theinvention is a computer readable medium having recorded thereon at least2, 5, 10, 15, or 20 of the sequences as set forth above.

Computer readable media include magnetically readable media, opticallyreadable media, electronically readable media and magnetic/opticalmedia. For example, the computer readable media may be a hard disk, afloppy disk, a magnetic tape, CD-ROM, Digital Versatile Disk (DVD),Random Access Memory (RAM), or Read Only Memory (ROM) as well as othertypes of other media known to those skilled in the art.

Embodiments of the invention include systems (e.g., internet basedsystems), particularly computer systems which store and manipulate thesequence information described herein. One example of a computer system100 is illustrated in block diagram form in FIG. 1. As used herein, “acomputer system” refers to the hardware components, software components,and data storage components used to analyze a nucleotide sequence of anucleic acid sequence as set forth in SEQ ID NO:1 nucleic acidsequences, and sequences substantially identical thereto, or apolypeptide sequence as set forth in the SEQ ID NO:2 amino acidsequences. The computer system 100 typically includes a processor forprocessing, accessing and manipulating the sequence data. The processor105 can be any well-known type of central processing unit, such as, forexample, the Pentium III from Intel Corporation, or similar processorfrom Sun, Motorola, Compaq, AMD or International Business Machines.

Typically the computer system 100 is a general purpose system thatcomprises the processor 105 and one or more internal data storagecomponents 110 for storing data, and one or more data retrieving devicesfor retrieving the data stored on the data storage components. A skilledartisan can readily appreciate that any one of the currently availablecomputer systems are suitable.

In one particular embodiment, the computer system 100 includes aprocessor 105 connected to a bus which is connected to a main memory 115(preferably implemented as RAM) and one or more internal data storagedevices 110, such as a hard drive and/or other computer readable mediahaving data recorded thereon. In some embodiments, the computer system100 further includes one or more data retrieving device 118 for readingthe data stored on the internal data storage devices 110.

The data retrieving device 118 may represent, for example, a floppy diskdrive, a compact disk drive, a magnetic tape drive, or a modem capableof connection to a remote data storage system (e.g., via the internet)etc. In some embodiments, the internal data storage device 110 is aremovable computer readable medium such as a floppy disk, a compactdisk, a magnetic tape, etc. containing control logic and/or datarecorded thereon. The computer system 100 may advantageously include orbe programmed by appropriate software for reading the control logicand/or the data from the data storage component once inserted in thedata retrieving device.

The computer system 100 includes a display 120 which is used to displayoutput to a computer user. It should also be noted that the computersystem 100 can be linked to other computer systems 125 a-c in a networkor wide area network to provide centralized access to the computersystem 100.

Software for accessing and processing the nucleotide sequences of anucleic acid sequence as set forth in SEQ ID NO:1 nucleic acidsequences, and sequences substantially identical thereto, or apolypeptide sequence as set forth in SEQ ID NO:2 amino acid sequences,and sequences substantially identical thereto, (such as search tools,compare tools, and modeling tools etc.) may reside in main memory 115during execution.

In some embodiments, the computer system 100 may further comprise asequence comparison algorithm for comparing a nucleic acid sequence asset forth in SEQ ID NO:1 nucleic acid sequences, and sequencessubstantially identical thereto, or a polypeptide sequence as set forthin SEQ ID NO:2 amino acid sequences, and sequences substantiallyidentical thereto, stored on a computer readable medium to a referencenucleotide or polypeptide sequence(s) stored on a computer readablemedium. A “sequence comparison algorithm” refers to one or more programswhich are implemented (locally or remotely) on the computer system 100to compare a nucleotide sequence with other nucleotide sequences and/orcompounds stored within a data storage means. For example, the sequencecomparison algorithm may compare the nucleotide sequences of a nucleicacid sequence as set forth in SEQ ID NO:1 nucleic acid sequences, andsequences substantially identical thereto, or a polypeptide sequence asset forth in SEQ ID NO:2 amino acid sequences, and sequencessubstantially identical thereto, stored on a computer readable medium toreference sequences stored on a computer readable medium to identifyhomologies or structural motifs. Various sequence comparison programsidentified elsewhere in this patent specification are particularlycontemplated for use in this aspect of the invention. Protein and/ornucleic acid sequence homologies may be evaluated using any of thevariety of sequence comparison algorithms and programs known in the art.Such algorithms and programs include, but are by no means limited to,TBLASTN, BLASTP, FASTA, TFASTA, and CLUSTALW (Pearson and Lipman, Proc.Natl. Acad. Sci. USA 85(8):2444-2448, 1988; Altschul et al., J. Mol.Biol. 215(3):403-410, 1990; Thompson et al., Nucleic Acids Res.22(2):4673-4680, 1994; Higgins et al., Methods Enzymol. 266:383-402,1996; Altschul et al., J. Mol. Biol. 215(3):403-410, 1990; Altschul etal., Nature Genetics 3:266-272, 1993).

Homology or identity is often measured using sequence analysis software(e.g., Sequence Analysis Software Package of the Genetics ComputerGroup, University of Wisconsin Biotechnology Center, 1710 UniversityAvenue, Madison, Wis. 53705). Such software matches similar sequences byassigning degrees of homology to various deletions, substitutions andother modifications. The terms “homology” and “identity” in the contextof two or more nucleic acids or polypeptide sequences, refer to two ormore sequences or subsequences that are the same or have a specifiedpercentage of amino acid residues or nucleotides that are the same whencompared and aligned for maximum correspondence over a comparison windowor designated region as measured using any number of sequence comparisonalgorithms or by manual alignment and visual inspection.

For sequence comparison, typically one sequence acts as a referencesequence, to which test sequences are compared. When using a sequencecomparison algorithm, test and reference sequences are entered into acomputer, subsequence coordinates are designated, if necessary, andsequence algorithm program parameters are designated. Default programparameters can be used, or alternative parameters can be designated. Thesequence comparison algorithm then calculates the percent sequenceidentities for the test sequences relative to the reference sequence,based on the program parameters.

A “comparison window”, as used herein, includes reference to a segmentof any one of the number of contiguous positions selected from the groupconsisting of from 20 to 600, usually about 50 to about 200, moreusually about 100 to about 150 in which a sequence may be compared to areference sequence of the same number of contiguous positions after thetwo sequences are optimally aligned. Methods of alignment of sequencefor comparison are well-known in the art. Optimal alignment of sequencesfor comparison can be conducted, e.g., by the local homology algorithmof Smith & Waterman, Adv. Appl. Math. 2:482, 1981, by the homologyalignment algorithm of Needleman & Wunsch, J. Mol. Biol 48:443, 1970, bythe search for sunilarity method of person & Lipman, Proc. Nat'l. Acad.Sci. USA 85:2444, 1988, by computerized implementations of thesealgoritluns (GAP, BESTFIT, FASTA, and TEASTA in the Wisconsin GeneticsSoftware Package, Genetics Computer Group, 575 Science Dr., Madison,Wis.), or by manual alignment and visual inspection. Other algorithmsfor detennining homology or identity include, for example, in additionto a BLAST program (Basic Local Alignment Search Tool at the NationalCenter for Biological Information), ALIGN, AMAS (Analysis of MultiplyAligned Sequences), AMPS (Protein Multiple Sequence Alignment), ASSET(Aligned Segment Statistical Evaluation Tool), BANDS, BESTSCOR, BIOSCAN(Biological Sequence Comparative Analysis Node), BLIMPS (BLocks IMProvedSearcher), FASTA, Intervals & Points, BMB, CLUSTAL V. CLUSTAL W,CONSENSUS, LCONSENSUS, WCONSENSUS, Smith-Waterman algorithm, DARWIN, LasVegas algorithm, FNAT (Forced Nucleotide Alignment Tool), Framealign,Framesearch, DYNAMIC, FILTER, FSAP (Fristeusky Sequence AnalysisPackage), GAP (Global Alignment Program), GENAL, GIBBS, GenQuest, ISSC(Sensitive Sequence Comparison), LALIGN (Local Sequence Alignment), LCP(Local Content Program), MACAW (Multiple Alignment Construction &Analysis Workbench), MAP (Multiple Alignment Program), MBLKP, MBLKN,PIMA (Pattern-Induced Multi-sequence Alignment), SAGA (SequenceAlignment by Genetic Algorithm) and WHAT-IF. Such alignment programs canalso be used to screen genome databases to identify polynucleotidesequences having substantially identical sequences. A number of genomedatabases arc available, for example, a substantial portion of the humangenome is available as part of the Human Genome Sequencing Project(Gibbs, 1995). At least twenty-one other genomes have already beensequenced, including, for example, M. genitalium (Fraser et at., 1995),M. jannaschii (Bult et al., 1996), H. influenzae (Fleischmann et al.,1995), E. coli (Blattner et al, 1997), and yeast (S. cerevisiae) (Meweset al., 1997), and D. melanogaster (Adams et al., 2000). Significantprogress has also been made in sequencing the genomes of model organism,such as mouse, C. elegans, and Arabadopsis sp. Several databasescontaining genomic information annotated with some functionalinformation are maintained by different organization, and are accessiblevia the internet.

One example of a useful algorithm is BLAST and BLAST 2.0 algorithms,which are described in Altschul et al., Nuc. Acids Res. 25:3389-3402,1977, and Altschul et al., J. Mol. Biol. 215:403-410, 1990,respectively. Software for performing BLAST analyses is publiclyavailable through the National Center for Biotechnology Information.This algorithm involves first identifying high scoring sequence pairs(HSPs) by identifying short words of length W in the query sequence,which either match or satisfy some positive-valued threshold score Twhen aligned with a word of the same length in a database sequence. T isreferred to as the neighborhood word score threshold (Altschul et at,supra). These initial neighborhood word hits act as seeds for initiatingsearches to find longer HSPs containing them. The word hits are extendedin both directions along each sequence for as far as the cumulativealignment score can be increased. Cumulative scores are calculatedusing, for nucleotide sequences, the parameters M (reward score for apair of matching residues; always >0). For amino acid sequences, ascoring matrix is used to calculate the cumulative score. Extension ofthe word hits in each direction are baited when: the cumulativealigmnent score falls off by the quantity X from its maximum achievedvalue; the cumulative score goes to zero or below, due to theaccumulation of one or more negative-scoring residue alignments; or theend of either sequence is reached. The BLAST algorithm parameters W, T,and X determine the sensitivity and speed of the alignment. The BLASTNprogram (for nucleotide sequences) uses as defaults a wordlength (W) of11, an expectation (E) of 10, M=5, N=−4 and a comparison of bothstrands. For amino acid sequences, the BLASTP program uses as defaults awordlength of 3, and expectations (E) of 10, and the BLOSUM62 scoringmatrix (see Henikoff & Henikoff, Proc. Natl. Acad. Sci. USA 89:10915,1989) alignments (B) of 50, expectation (E) of 10, M=5, N=−4, and acomparison of both strands.

The BLAST algorithm also performs a statistical analysis of thesimilarity between two sequences (see, e.g., Karlin & Altschul, Proc.Natl. Acad. Sci. USA 90:5873, 1993). One measure of similarity providedby BLAST algorithm is the smallest sum probability (P(N)), whichprovides an indication of the probability by which a match between twonucleotide or amino acid sequences would occur by chance. For example, anucleic acid is considered similar to a references sequence if thesmallest sum probability in a comparison of the test nucleic acid to thereference nucleic acid is less than about 0.2, more preferably less thanabout 0.01, and most preferably less than about 0.001.

In one embodiment, protein and nucleic acid sequence homologies areevaluated using the Basic Local Alignment Search Tool (“BLAST”) Inparticular, five specific BLAST programs are used to perform thefollowing task:

(1) BLASTP and BLAST3 compare an amino acid query sequence against aprotein sequence database;

(2) BLASTN compares a nucleotide query sequence against a nucleotidesequence database;

(3) BLASTX compares the six-frame conceptual translation products of aquery nucleotide sequence (both strands) against a protein sequencedatabase;

(4) TBLASTN compares a query protein sequence against a nucleotidesequence database translated in all six reading frames (both strands);and

(5) TBLASTX compares the six-frame translations of a nucleotide querysequence against the six-frame translations of a nucleotide sequencedatabase.

The BLAST programs identify homologous sequences by identifying similarsegments, which are referred to herein as “high-scoring segment pairs,”between a query amino or nucleic acid sequence and a test sequence whichis preferably obtained from a protein or nucleic acid sequence database.High-scoring segment pairs are preferably identified (i.e., aligned) bymeans of a scoring matrix, many of which are known in the art.Preferably, the scoring matrix used is the BLOSUM62 matrix (Gonnet etal., Science 256:1443-1445, 1992; Henikoff and Henikoff, Proteins17:49-61, 1993). Less preferably, the PAM or PAM250 matrices may also beused (see, e.g., Schwartz and Dayhoff, eds., 1978, Matrices forDetecting Distance Relationships: Atlas of Protein Sequence andStructure, Washington: National Biomedical Research Foundation). BLASTprograms are accessible through the U.S. National Library of Medicine.

The parameters used with the above algorithms may be adapted dependingon the sequence length and degree of homology studied. In someembodiments, the parameters may be the default parameters used by thealgorithms in the absence of instructions from the user.

FIG. 2 is a flow diagram illustrating one embodiment of a process 200for comparing a new nucleotide or protein sequence with a database ofsequences in order to determine the homology levels between the newsequence and the sequences in the database. The database of sequencescan be a private database stored within the computer system 100, or apublic database such as GENBANK that is available through the Internet.

The process 200 begins at a start state 201 and then moves to a state202 wherein the new sequence to be compared is stored to a memory in acomputer system 100. As discussed above, the memory could be any type ofmemory, including RAM or an internal storage device.

The process 200 then moves to a state 204 wherein a database ofsequences is opened for analysis and comparison. The process 200 thenmoves to a state 206 wherein the first sequence stored in the databaseis read into a memory on the computer. A comparison is then performed ata state 210 to determine if the first sequence is the same as the secondsequence. It is important to note that this step is not limited toperforming an exact comparison between the new sequence and the firstsequence in the database. Well-known methods are known to those of skillin the art for comparing two nucleotide or protein sequences, even ifthey are not identical. For example, gaps can be introduced into onesequence in order to raise the homology level between the two testedsequences. The parameters that control whether gaps or other featuresare introduced into a sequence during comparison are normally entered bythe user of the computer system.

Once a comparison of the two sequences has been performed at the state210, a determination is made at a decision state 210 whether the twosequences are the same. Of course, the term “same” is not limited tosequences that are absolutely identical. Sequences that are within thehomology parameters entered by the user will be marked as “same” in theprocess 200.

If a determination is made that the two sequences are the same, theprocess 200 moves to a state 214 wherein the name of the sequence fromthe database is displayed to the user. This state notifies the user thatthe sequence with the displayed name fulfills the homology constraintsthat were entered. Once the name of the stored sequence is displayed tothe user, the process 200 moves to a decision state 218 wherein adetermination is made whether more sequences exist in the database. Ifno more sequences exist in the database, then the process 200 terminatesat an end state 220. However, if more sequences do exist in thedatabase, then the process 200 moves to a state 224 wherein a pointer ismoved to the next sequence in the database so that it can be compared tothe new sequence. In this manner, the new sequence is aligned andcompared with every sequence in the database.

It should be noted that if a determination had been made at the decisionstate 212 that the sequences were not homologous, then the process 200would move immediately to the decision state 218 in order to determineif any other sequences were available in the database for comparison.

Accordingly, one aspect of the invention is a computer system comprisinga processor, a data storage device having stored thereon a nucleic acidsequence as set forth in SEQ ID NO:1 nucleic acid sequences, andsequences substantially identical thereto, or a polypeptide sequence asset forth in SEQ ID NO:2 amino acid sequences, and sequencessubstantially identical thereto, a data storage device havingretrievably stored thereon reference nucleotide sequences or polypeptidesequences to be compared to a nucleic acid sequence as set forth in SEQID NO:1 nucleic acid sequences, and sequences substantially identicalthereto, or a polypeptide sequence as set forth in SEQ ID NO:2 aminoacid sequences, and sequences substantially identical thereto, and asequence comparer for conducting the comparison. The sequence comparermay indicate a homology level between the sequences compared or identifystructural motifs in the above described nucleic acid code of SEQ IDNO:1 nucleic acid sequences, and sequences substantially identicalthereto, or a polypeptide sequence as set forth in SEQ ID NO:2 aminoacid sequences, and sequences substantially identical thereto, or it mayidentify structural motifs in sequences which are compared to thesenucleic acid codes and polypeptide codes. In some embodiments, the datastorage device may have stored thereon the sequences of at least 2, 5,10, 15, 20, 25, 30 or 40 or more of the nucleic acid sequences as setforth in SEQ ID NO:1 nucleic acid sequences, and sequences substantiallyidentical thereto, or the polypeptide sequences as set forth in SEQ IDNO:2 amino acid sequences, and sequences substantially identicalthereto.

Another aspect of the invention is a method for determining the level ofhomology between a nucleic acid sequence as set forth in SEQ ID NO:1nucleic acid sequences, and sequences substantially identical thereto,or a polypeptide sequence as set forth in SEQ ID NO:2 amino acidsequences, and sequences substantially identical thereto, and areference nucleotide sequence. The method including reading the nucleicacid code or the polypeptide code and the reference nucleotide orpolypeptide sequence through the use of a computer program whichdetermines homology levels and determining homology between the nucleicacid code or polypeptide code and the reference nucleotide orpolypeptide sequence with the computer program. The computer program maybe any of a number of computer programs for determining homology levels,including those specifically enumerated herein, (e.g., BLAST2N with thedefault parameters or with any modified parameters). The method may beimplemented using the computer systems described above. The method mayalso be performed by reading at least 2, 5, 10, 15, 20, 25, 30 or 40 ormore of the above described nucleic acid sequences as set forth in theSEQ ID NO:1 nucleic acid sequences, or the polypeptide sequences as setforth in the SEQ ID NO:2 amino acid sequences through use of thecomputer program and determining homology between the nucleic acid codesor polypeptide codes and reference nucleotide sequences or polypeptidesequences.

FIG. 3 is a flow diagram illustrating one embodiment of a process 250 ina computer for determining whether two sequences are homologous. Theprocess 250 begins at a start state 252 and then moves to a state 254wherein a first sequence to be compared is stored to a memory. Thesecond sequence to be compared is then stored to a memory at a state256. The process 250 then moves to a state 260 wherein the firstcharacter in the first sequence is read and then to a state 262 whereinthe first character of the second sequence is read. It should beunderstood that if the sequence is a nucleotide sequence, then thecharacter would normally be either A, T, C, G or U. If the sequence is aprotein sequence, then it is preferably in the single letter amino acidcode so that the first and sequence sequences can be easily compared.

A determination is then made at a decision state 264 whether the twocharacters are the same. If they are the same, then the process 250moves to a state 268 wherein the next characters in the first and secondsequences are read. A determination is then made whether the nextcharacters are the same. If they are, then the process 250 continuesthis loop until two characters are not the same. If a determination ismade that the next two characters are not the same, the process 250moves to a decision state 274 to determine whether there are any morecharacters either sequence to read.

If there are not any more characters to read, then the process 250 movesto a state 276 wherein the level of homology between the first andsecond sequences is displayed to the user. The level of homology isdetermined by calculating the proportion of characters between thesequences that were the same out of the total number of sequences in thefirst sequence. Thus, if every character in a first 100 nucleotidesequence aligned with a every character in a second sequence, thehomology level would be 100%.

Alternatively, the computer program may be a computer program whichcompares the nucleotide sequences of a nucleic acid sequence as setforth in the invention, to one or more reference nucleotide sequences inorder to determine whether the nucleic acid code of SEQ ID NO:1 nucleicacid sequences, and sequences substantially identical thereto, differsfrom a reference nucleic acid sequence at one or more positions.Optionally such a program records the length and identity of inserted,deleted or substituted nucleotides with respect to the sequence ofeither the reference polynucleotide or a nucleic acid sequence as setforth in SEQ ID NO:1 nucleic acid sequences, and sequences substantiallyidentical thereto. In one embodiment, the computer program may be aprogram which determines whether a nucleic acid sequence as set forth inSEQ ID NO:1 nucleic acid sequences, and sequences substantiallyidentical thereto, contains a single nucleotide polymorphism (SNP) withrespect to a reference nucleotide sequence.

Accordingly, another aspect of the invention is a method for determiningwhether a nucleic acid sequence as set forth in SEQ ID NO:1 nucleic acidsequences, and sequences substantially identical thereto, differs at oneor more nucleotides from a reference nucleotide sequence comprising thesteps of reading the nucleic acid code and the reference nucleotidesequence through use of a computer program which identifies differencesbetween nucleic acid sequences and identifying differences between thenucleic acid code and the reference nucleotide sequence with thecomputer program. In some embodiments, the computer program is a programwhich identifies single nucleotide polymorphisms. The method may beimplemented by the computer systems described above and the methodillustrated in FIG. 3. The method may also be performed by reading atleast 2, 5, 10, 15, 20, 25, 30, or 40 or more of the nucleic acidsequences as set forth in SEQ ID NO:1 nucleic acid sequences, andsequences substantially identical thereto, and the reference nucleotidesequences through the use of the computer program and identifyingdifferences between the nucleic acid codes and the reference nucleotidesequences with the computer program.

In other embodiments the computer based system may further comprise anidentifier for identifying features within a nucleic acid sequence asset forth in the SEQ ID NO:1 nucleic acid sequences or a polypeptidesequence as set forth in SEQ ID NO:2 amino acid sequences, and sequencessubstantially identical thereto.

An “identifier” refers to one or more programs which identifies certainfeatures within a nucleic acid sequence as set forth in SEQ ID NO:1nucleic acid sequences, and sequences substantially identical thereto,or a polypeptide sequence as set forth in SEQ ID NO:2 amino acidsequences, and sequences substantially identical thereto. In oneembodiment, the identifier may comprise a program which identifies anopen reading frame in a nucleic acid sequence as set forth in SEQ IDNO:1 nucleic acid sequences, and sequences substantially identicalthereto.

FIG. 4 is a flow diagram illustrating one embodiment of an identifierprocess 300 for detecting the presence of a feature in a sequence. Theprocess 300 begins at a start state 302 and then moves to a state 304wherein a first sequence that is to be checked for features is stored toa memory 115 in the computer system 100. The process 300 then moves to astate 306 wherein a database of sequence features is opened. Such adatabase would include a list of each feature's attributes along withthe name of the feature. For example, a feature name could be“Initiation Codon” and the attribute would be “ATG”. Another examplewould be the feature name “TAATAA Box” and the feature attribute wouldbe “TAATAA”. An example of such a database is produced by the Universityof Wisconsin Genetics Computer Group (www.gcg.com). Alternatively, thefeatures may be structural polypeptide motifs such as alpha helices,beta sheets, or functional polypeptide motifs such as enzymatic activesites, helix-turn-helix motifs or other motifs known to those skilled inthe art.

Once the database of features is opened at the state 306, the process300 moves to a state 308 wherein the first feature is read from thedatabase. A comparison of the attribute of the first feature with thefirst sequence is then made at a state 310. A determination is then madeat a decision state 316 whether the attribute of the feature was foundin the first sequence. If the attribute was found, then the process 300moves to a state 318 wherein the name of the found feature is displayedto the user.

The process 300 then moves to a decision state 320 wherein adetermination is made whether move features exist in the database. If nomore features do exist, then the process 300 terminates at an end state324. However, if more features do exist in the database, then theprocess 300 reads the next sequence feature at a state 326 and loopsback to the state 310 wherein the attribute of the next feature iscompared against the first sequence.

It should be noted, that if the feature attribute is not found in thefirst sequence at the decision state 316, the process 300 moves directlyto the decision state 320 in order to determine if any more featuresexist in the database.

Accordingly, another aspect of the invention is a method of identifyinga feature within a nucleic acid sequence as set forth in SEQ ID NO:1nucleic acid sequences, and sequences substantially identical thereto,or a polypeptide sequence as set forth in SEQ ID NO:2 amino acidsequences, and sequences substantially identical thereto, comprisingreading the nucleic acid code(s) or polypeptide code(s) through the useof a computer program which identifies features therein and identifyingfeatures within the nucleic acid code(s) with the computer program. Inone embodiment, computer program comprises a computer program whichidentifies open reading frames. The method may be performed by reading asingle sequence or at least 2, 5, 10, 15, 20, 25, 30, or 40 of thenucleic acid sequences as set forth in SEQ ID NO:1 nucleic acidsequences, and sequences substantially identical thereto, or thepolypeptide sequences as set forth in SEQ ID NO:2 amino acid sequences,and sequences substantially identical thereto, through the use of thecomputer program and identifying features within the nucleic acid codesor polypeptide codes with the computer program.

A nucleic acid sequence as set forth in SEQ ID NO:1 nucleic acidsequences, and sequences substantially identical thereto, or apolypeptide sequence as set forth in SEQ ID NO:2 amino acid sequences,and sequences substantially identical thereto, may be stored andmanipulated in a variety of data processor programs in a variety offormats. For example, a nucleic acid sequence as set forth in SEQ IDNO:1 nucleic acid sequences, and sequences substantially identicalthereto, or a polypeptide sequence as set forth in SEQ ID NO:2 aminoacid sequences, and sequences substantially identical thereto, may bestored as text in a word processing file, such as MicrosoftWORD orWORDPERFECT or as an ASCII file in a variety of database programsfamiliar to those of skill in the art, such as DB2, SYBASE, or ORACLE.In addition, many computer programs and databases may be used assequence comparison algorithms, identifiers, or sources of referencenucleotide sequences or polypeptide sequences to be compared to anucleic acid sequence as set forth in SEQ ID NO:1 nucleic acidsequences, and sequences substantially identical thereto, or apolypeptide sequence as set forth in SEQ ID NO:2 amino acid sequences,and sequences substantially identical thereto. The following list isintended not to limit the invention but to provide guidance to programsand databases which are useful with the nucleic acid sequences as setforth in SEQ ID NO:1 nucleic acid sequences, and sequences substantiallyidentical thereto, or the polypeptide sequences as set forth in SEQ IDNO:2 amino acid sequences, and sequences substantially identicalthereto.

The programs and databases which may be used include, but are notlimited to: MacPattern (EMBL), DiscoveryBase (Molecular ApplicationsGroup), GeneMine (Molecular Applications Group), Look (MolecularApplications Group), MacLook (Molecular Applications Group), BLAST andBLAST2 (NCBI), BLASTN and BLASTX (Altschul et al, J. Mol. Biol. 215:403, 1990), FASTA (Pearson and Lipman, Proc. Natl. Acad. Sci. USA, 85:2444, 1988), FASTDB (Brutlag et al. Comp. App. Biosci. 6:237-245, 1990),Catalyst (Molecular Simulations Inc.), Catalyst/SHAPE (MolecularSimulations Inc.), Cerius2.DBAccess (Molecular Simulations Inc.),HypoGen (Molecular Simulations Inc.), Insight II, (Molecular SimulationsInc.), Discover (Molecular Simulations Inc.), CHARMm (MolecularSimulations Inc.), Felix (Molecular Simulations Inc.), DelPhi,(Molecular Simulations Inc.), QuanteMM, (Molecular Simulations Inc.),Homology (Molecular Simulations Inc.), Modeler (Molecular SimulationsInc.), ISIS (Molecular Simulations Inc.), Quanta/Protein Design(Molecular Simulations Inc.), WebLab (Molecular Simulations Inc.),WebLab Diversity Explorer (Molecular Simulations Inc.), Gene Explorer(Molecular Simulations Inc.), SeqFold (Molecular Simulations Inc.), theMDL Available Chemicals Directory database, the MDL Drug Data Reportdata base, the Comprehensive Medicinal Chemistry database, Derwent'sWorld Drug Index database, the BioByteMasterFile database, the Genbankdatabase, and the Genseqn database. Many other programs and data baseswould be apparent to one of skill in the art given the presentdisclosure.

Motifs which may be detected using the above programs include sequencesencoding leucine zippers, helix-turn-helix motifs, glycosylation sites,ubiquitination sites, alpha helices, and beta sheets, signal sequencesencoding signal peptides which direct the secretion of the encodedproteins, sequences implicated in transcription regulation such ashomeoboxes, acidic stretches, enzymatic active sites, substrate bindingsites, and enzymatic cleavage sites.

The present invention exploits the unique catalytic properties ofenzymes. Whereas the use of biocatalysts (i.e., purified or crudeenzymes, non-living or living cells) in chemical transformationsnormally requires the identification of a particular biocatalyst thatreacts with a specific starting compound, the present invention usesselected biocatalysts and reaction conditions that are specific forfunctional groups that are present in many starting compounds, such assmall molecules. Each biocatalyst is specific for one functional group,or several related functional groups, and can react with many startingcompounds containing this functional group.

The biocatalytic reactions produce a population of derivatives from asingle starting compound. These derivatives can be subjected to anotherround of biocatalytic reactions to produce a second population ofderivative compounds. Thousands of variations of the original smallmolecule or compound can be produced with each iteration of biocatalyticderivatization.

Enzymes react at specific sites of a starting compound without affectingthe rest of the molecule, a process which is very difficult to achieveusing traditional chemical methods. This high degree of biocatalyticspecificity provides the means to identify a single active compoundwithin the library. The library is characterized by the series ofbiocatalytic reactions used to produce it, a so called “biosynthetichistory”. Screening the library for biological activities and tracingthe biosynthetic history identifies the specific reaction sequenceproducing the active compound. The reaction sequence is repeated and thestructure of the synthesized compound determined. This mode ofidentification, unlike other synthesis and screening approaches, doesnot require immobilization technologies, and compounds can besynthesized and tested free in solution using virtually any type ofscreening assay. It is important to note, that the high degree ofspecificity of enzyme reactions on functional groups allows for the“tracking” of specific enzymatic reactions that make up thebiocatalytically produced library.

Many of the procedural steps are performed using robotic automationenabling the execution of many thousands of biocatalytic reactions andscreening assays per day as well as ensuring a high level of accuracyand reproducibility. As a result, a library of derivative compounds canbe produced in a matter of weeks which would take years to produce usingcurrent chemical methods.

In a particular embodiment, the invention provides a method formodifying small molecules, comprising contacting a polypeptide encodedby a polynucleotide described herein or enzymatically active fragmentsthereof with a small molecule to produce a modified small molecule. Alibrary of modified small molecules is tested to determine if a modifiedsmall molecule is present within the library which exhibits a desiredactivity. A specific biocatalytic reaction which produces the modifiedsmall molecule of desired activity is identified by systematicallyeliminating each of the biocatalytic reactions used to produce a portionof the library, and then testing the small molecules produced in theportion of the library for the presence or absence of the modified smallmolecule with the desired activity. The specific biocatalytic reactionswhich produce the modified small molecule of desired activity isoptionally repeated. The biocatalytic reactions are conducted with agroup of biocatalysts that react with distinct structural moieties foundwithin the structure of a small molecule, each biocatalyst is specificfor one structural moiety or a group of related structural moieties; andeach biocatalyst reacts with many different small molecules whichcontain the distinct structural moiety.

The invention will be further described with reference to the followingexamples; however, it is to be understood that the invention is notlimited to such examples.

EXAMPLES Example 1

Identification and Characterization of Thermostable α-Amylases

The present example shows the identification of novel acid amylases. Thescreening program was carried out under neutral and low pH conditions.DNA libraries generated from low pH samples were targeted for discovery.This effort afforded the discovery of hundreds of clones having theability to degrade starch. DNA sequence and bioinformatic analysesclassified many of these genes as previously unidentified amylases.

Biochemical Studies

Biochemical analysis of the amylase genomic clones showed that many hadpH optima of less than pH 6. Lysates of these genomic clones were testedfor thermal tolerance by incubation at 70° C., 80° C., 90° C. or 100° C.for 10 minutes and measurement of residual activity at pH 4.5. Thoseclones retaining >50% activity after heat treatment at 80° C. werechosen for further analysis. These clones were incubated at 90° C. for10 minutes at pH 6.0 and 4.5 and tested for residual activity at pH 4.5.A number of clones retained >40% of their activity following thistreatment. For comparative purposes, residual activity of an evolvedamylase, SEQ ID NO:2, was equivalent to the best of thesecond-generation enzymes; the specific activity of SEQ ID NO:2 wasgreater.

Thermal activity of the clones with residual activity after heattreatment at 90° C. at pH 4.5 was measured at room temperature, 70° C.and 90° C. at pH 4.5. Table 1 shows that the hydrolysis rates of SEQ IDNO.: 3 (B. stearothermophilus amylase) and SEQ ID NO.: 4 (B.licheniformis amylase) decrease at higher temperatures, whereas the ratefor SEQ ID NO.: 5 continues to increase as the temperature is raised to70° C. and only reduces by around 50% at 90° C.

Candidate Evaluation

Based on residual activity at pH 4.5 after a 90° C. heat treatment,specific activity and rate of starch hydrolysis at 90° C. when comparedwith B. licheniformis amylase, SEQ ID NO.: 5 is compared with theevolved amylase SEQ ID NO:2 in a starch liquefaction assay.

TABLE 1 Rates of dye labeled starch hydrolysis (relative fluorescenceunits/s) of three genomic clones at pH 4.5 and 3 different temperatures.Room temperature 70° C. 90° SEQ ID NO.: 3¹ 1.25 1.43 0.33 SEQ ID NO.: 4²3.3 1.9 0.39 SEQ ID NO.: 5 1.9 47 19 ¹ B. stearothermophilus amylase, ²B. licheniformis amylase

Example 2 Amylase Activity Assay: BCA Reducing Ends Assay

-   1. Prepare 2 substrate solutions, as follows:    -   a) 2% soluble starch (potato) pH 8 solution by dissolving 2 gm        potato starch in 100 ml 100 mM sodium phosphate pH 8).    -   b) 2% soluble starch (potato) pH 10 solution by dissolving 2 gm        potato starch in 100 ml 100 mM sodium carbonate.

Heat both solutions in a boiling water bath, while mixing, for 30-40minutes until starch dissolves.

-   2. Prepare Solution A from 64 mg/ml sodium carbonate monohydrate, 24    mg/ml sodium bicarbonate and 1.95 mg/ml BCA    (4,4′-dicarboxy-2,2′-biquinoline disodium salt (Sigma Chemical cat    #D-8284). Added above to dH2O.-   3. Prepare solution B by combining 1.24 mg/ml cupric sulfate    pentahydrate and 1.26 mg/ml L-serine. Add mixture to to dH2O.-   4. Prepare a working reagent of a 1:1 ration of solutions A and B.-   5. Prepare a Maltose standard solution of 10 mM Maltose in dH2O,    where the 10 mM maltose is combined in 2% soluble starch at desired    pH to a final concentration of 0, 100, 200, 300, 400, 600 μM. The    standard curve will be generated for each set of time-points. Since    the curve is determined by adding 10 ul of the standards to the    working reagent it works out to 0, 1, 2, 3, 4, 6 nmole maltose.-   6. Aliquot 1 ml of substrate solution into microcentrifuge tubes,    equilibrate to desired temperature (5 min) in heat block or heated    water bath. Add 50 ul of enzyme solution to the inside of the tube    lid.-   7. While solution is equilibrating mix 5 ml of both solution A & B.    Aliquot 100 ul to 96 well PCR plate. Set plate on ice.-   8. After 5 minute temperature equilibration, close lid on tubes,    invert and vortex 3 times. Immediately aliquot 10 ul into plate as    t=0 (zero time point). Leave enzyme mixture in heat block and    aliquot 10 ul at each desired time point (e.g. 0, 5, 10, 15, 20, 30    minutes).-   9. Ensure that 12 wells are left empty (only working reagent    aliquotted) for the addition of 10 ul of standards, for the standard    curve.-   10. When all time points are collected and standards are added,    cover plate and heated to 80° C. for 35 min. Cool plate on ice for    10 min. Add 100 ul H2O to all wells. Mix and aliquot 100 ul into    flat bottomed 96-well plate and read absorbance at 560 nm.-   11. Zero each sample's time points against its own t=0 (subtract the    average t=0 A560 value from other average A560 values). Convert the    A⁵⁶⁰ _((experimental)) to umole (Divide A⁵⁶⁰ _((experimental)) by    the slope of the standard curve (A560/umole). Generate a slope of    the time points and the umole (in umole/min), multiply by 100 (as    the umole value only accounts for the 10 ul used in the assay, not    the amount made in the 1 ml rxn). To get the specific activity    divide the slope (in umole/min) by the mg of protein. All points    should be done at a minimum in duplicate with three being best. An    example standard curve is set forth in FIG. 5.

TABLE 2 Sample data: (A560exp/ std Di- Avg Zeroed slope) Clone lutionMinutes A560-1 A560-2 A 560 A 560 umole ENZ 50 0 0.1711 0.1736 0.17235 00.0000 5 0.2104 0.2165 0.21345 0.0411 0.0005 10 0.2492 0.2481 0.248650.0763 0.0009 15 0.2984 0.2882 0.2933 0.12095 0.0014 20 0.3355 0.34090.3382 0.16585 0.0020 30 0.3942 0.3805 0.38735 0.215 0.0026 40 0.45010.4412 0.44565 0.2733 0.0033

Example 3 Screening for α-Amylase Activity

The number of plaques screened, per plate, should be approximately10,000 pfu's. For each DNA library: at least 50,000 plaques per isolatedlibrary and 200,000 plaques per non-isolated library should be screeneddepending upon the pfu titer for the λ Zap Express amplified lysate.

Titer Determination of Lambda Library

-   1) μL of Lambda Zap Express amplified library stock added to 600    μL E. coli MRF′ cells (OD₆₀₀=1.0). To dilute MRF′ stock, 10 mM MgSO₄    is used.-   2) Incubate at 37° C. for 15 minutes.-   3) Transfer suspension to 5-6 mL of NZY top agar at 50° C. and    gently mix.-   4) Immediately pour agar solution onto large (150 mm) NZY media    plate.-   5) Allow top agar to solidify completely (approximately 30 minutes),    then invert plate.-   6) Incubate the plate at 39° C. for 8-12 hours.-   7) Number of plaques is approximated. Phage titer determined to give    10,000 pfu/plate. Dilute an aliquot of Library phage with SM buffer    if needed.    Substrate Screening-   1) Lambda Zap Express (50,000 pfu) from amplified library added to    600 μL of E. coli MRF′ cells (OD600=1.0). For non-environment    libraries, prepare 4 tubes (50,000 pfu per tube).-   2) Incubate at 37° C. for 15 minutes.-   3) While phage/cell suspension are incubating, 1.0 mL of red starch    substrate (1.2% w/v) is added to 6.0 mL NZY top agar at 50° C. and    mixed thoroughly. Keep solution at 50° C. until needed.-   4) Transfer ⅕ (10,000 pfu) of the cell suspension to substrate/top    agar solution and gently mixed.-   5) Solution is immediately poured onto large (150 mm) NZY media    plate.-   6) Allow top agar to solidify completely (approximately 30 minutes),    then invert plate.-   7) Repeat procedures 4-6 4 times for the rest of the cell suspension    (⅕ of the suspension each time).-   8) Incubate plates at 39° C. for 8-12 hours.-   9) Plate observed for clearing zones (halos) around plaques.-   10) Plaques with halos are cored out of agar and transferred to a    sterile micro tube. A large bore 200 μL pipette tip works well to    remove (core) the agar plug containing the desired plaque.-   11) Phages are re-suspended in 500 μL SM buffer. 20 μL Chloroform is    added to inhibit any further cell growth.-   12) Pure phage suspension is incubated at room temperature for 4    hours or overnight before next step.    Isolation of Pure Clones-   1) 10 μL of re-suspended phage suspension is added to 500 μL of E.    coli MRF' cells (OD600=1.0).-   2) Incubate at 37° C. for 15 minutes.-   3) While phage/cell suspension is incubating, 1 mL of red starch    substrate (1.2% w/v) is added to 6.0 mL NZY top agar at 50° C. and    mixed thoroughly. Keep solution at 50° C. until needed.-   4) Cell suspension is transferred to substrate/top agar solution and    gently mixed.-   5) Solution is immediately poured onto large (150 mm) NZY media    plate.-   6) Allow top agar to solidify completely (approximately 30 minutes),    then invert plate.-   7) Plate incubated at 39° C. for 8-12 hours.-   8) Plate observed for a clearing zone (halo) around a single plaque    (pure clone). If a single plaque cannot be isolated, adjust titer    and re-plate phage suspension.-   9) Single plaque with halo is cored out of agar and transferred to a    sterile micro tube. A large bore 200 μL pipette tip works well to    remove (core) the agar plug containing the desired plaque. To    amplify the titer, core 5 single active plaques into a micro tube.-   10) Phages are re-suspended in 500 μL SM buffer. 20 μL Chloroform is    added to inhibit any further cell growth.-   11) Pure phage suspension is incubated at room temperature for 4    hours or overnight before next step. The pure phage suspension is    stored at −80° C. by adding DMSO into the phage suspension (7% v/v).    Excision of Pure Clone-   1) 100 μL of pure phage suspension is added to 200 μL E. coli MRF'    cells (OD600=1.0). To this, 1.0 μL of ExAssist helper phage (>1×106    pfu/mL;Stratagene) is added. Use 2059 Falcon tube for excision.-   2) Suspension is incubated at 37° C. for 15 minutes.-   3) 3.0 mL of 2×YT media is added to cell suspension.-   4) Incubate at 30° C. for at least 6 hours or overnight while    shaking.-   5) Tube transferred to 70° C. for 20 minutes. The phagemid    suspension can be stored at 4° C. for 1 to 2 months.-   6) 100 μL of phagemid suspension transferred to a micro tube    containing 200 μL of E. coli Exp 505 cells (OD600=1.0).-   7) Suspension incubated at 37° C. for 15 minutes.-   8) 300 μL of SOB is added to the suspension.-   9) Suspension is incubated at 37° C. for 30 to 45 minutes.-   10) 100 μL of suspension is transferred to a small (90 mm) LB media    plate containing Kanamycin (LB media with Kanamycin 50 μg/mL) for    Zap Express DNA libraries or Ampicillin (LB media with Kanamycin 100    μg/mL) for Zap II DNA libraries.-   11) The rest of suspension is transferred to another small LB media    plate.-   12) Use sterile glass beads to evenly distribute suspension on the    plate.-   13) Plates are incubated at 30° C. for 12 to 24 hours.-   14) Plate observed for colonies.-   15) Inoculate single colony into LB liquid media containing suitable    antibiotic and incubate at 30° C. for 12 to 24 hours.-   16) Glycerol stock can be prepared by adding 80% glycerol into    liquid culture (15% v/v) and stored at −80° C.    Activity Verification-   1) 50 μL of liquid culture is transferred to a micro tube. Add 500    μL of 8% pH7 Amylopectin Azure into the same tube. Prepare 2 tubes    for each clone.-   2) Activity is tested at 50° C. for 3 hours and overnight. Use pH 7    buffer as control.-   3) Cool the test specimen at ice-water bath for 5 minutes.-   4) Add 750 μL of Ethaqnol and mixed thoroughly.-   5) Centrifuge at 13000 rpm (16000 g's) for 5 minutes.-   6) Measure OD of the supernatant at 595 nm.    RFLP Analysis-   1) 1.0 mL of liquid culture is transferred to a sterile micro tube.-   2) Centrifuge at 13200 rpm (16000 g's) for 1 minute.-   3) Discard the supernatant. Add another 1.0 mL of liquid culture    into the same sterile micro tube.-   4) Centrifuge at 13200 rpm (16000 g's) for 1 minute.-   5) Discard the supernatant.-   6) Follow QlAprep spin mini kit protocol for plasmid isolation.-   7) Check DNA concentration using BioPhotometer.-   8) Use Sac I and Kpn I for first double digestion. Incubate at    37° C. for 1 hour.-   9) Use Pst I and Xho I for second double digestion. Incubate at    37° C. for 1 hour.-   10) Add Loading dye into the digested sample.-   11) Run the digested sample on a 1.0% agarose gel for 1-1.5 hours at    120 volts.-   12) View gel with gel imager. All clones with a different digest    pattern will be sent for sequence analysis.

Example 4 Assay for Amylases

Preparation of Host Cultures

-   1. Start an overnight culture of XL1-Blue MRF' host cells. Use a    single colony from a streak plate to inoculate 10 mL LB supplemented    with 20 ug/mL tetracycline. Grow overnight culture shaking at 37° C.    for at least 16 hours.-   2. Using aseptic technique, inoculate a fresh 100 mL of LB_(Tet) day    culture with XL1-Blue MRF' host from the overnight LB_(Tet) culture.-   3. Grow in a 37° C. shaker until the OD reaches 0.75-1.0.-   4. Pellet host cells at 1000×g for 10 minutes and gently resuspend    in 10 mM MgSO₄ at OD5.-   5. Dilute a small amount of host cells to OD1 for use in titering    and pintooling.-   6. Host preparations can be used for up to 1 week when stored on ice    or at 4° C.

Comments

-   -   To shorten growth time for the day culture, use ½× the usual Tet        concentration in LB (½×=10 ug/mL), or omit the antibiotic        altogether.

    -   

Do not use NZY when selecting with Tetracycline. The high Mg⁺⁺concentration in NZY medium renders Tet inactive.

Titering Lambda Libraries

-   7. Placed three sterile microfuge tubes in a rack.-   8. Aliquoted 995 uL prepared host cells in one tube and 45 uL    prepared OD1 host cells into each of the two remaining tubes.-   9. Added 5 uL of lambda library to the tube containing 995 uL host    cells and mixed by vortexing. This resulted in a dilution factor of    200.-   10. Prepared 1/2,000 and 1/20,000 dilutions by consecutively adding    5 uL of previous dilution to the remaining two tubes containing 45    uL prepared host cells. Mixed by vortexing after each dilution was    made.-   11. Phage allowed to adsorb to host by incubating at 37° C. for 15    minutes.-   12. Meanwhile, pipetted 100 uL of prepared OD1 host cells to each of    three Falcon 2059 tubes.-   13. Added 5 uL of each dilution to a separate 2059 tube containing    host cells.-   14. Plated each by adding 3 mL top agar to each tube and quickly    pouring over 90 mm NZY plates. Ensured a smooth, even distribution    before the top agar hardens.-   15. Inverted plates and incubated at 37° C. overnight.-   16. Counted plaques and calculated titer of the library stock (in    plaque forming units (pfu) per uL).

1.

Lambda Microtiter Screening For Amylases

Preparation

Prepare a sufficient amount of XL1-Blue MRF' host culture, as describedabove, for the amount of screening planned.

-   1. Autoclave several bottles compatible with the QFill2 dispenser.    These are the wide-mouth Corning bottles, 250 mL containing a    sealing ring around the lip.-   2. Make sure there are sufficient amounts of plates, top agar,    BODIPY starch, red starch solution, etc. available for the screen.-   3. Schedule the Day 2 robot run with a representative from    Automation.

Day 1

-   1. Label the 1536-well plates (black) with library screen and plate    number. Tough-Tags™ tube stickers, cut in half width-wise, are ideal    for labeling 1536 well plates.-   2. Calculate volumes of library, host cells and NZY medium necessary    for the screen. This is easily done with an Excel spreadsheet.-   3. Combine the calculated volumes of lambda library and OD5 host    cells in a sterile 250 mL wide-mouth Corning bottle (containing a    sealing ring).-   4. Allow adsorption to occur at 37° C. for 15 minutes.-   5. Add the calculated volume of NZY medium and mix well. This is    referred to as the cell-phage-medium suspension.-   6. Perform a concomitant titer by combining 50 uL of the    cell-phage-medium suspension with 250 uL of OD1 host cells in a    Falcon 2059 tube, then plating with 9 mL of top agar onto a 150 mm    NZY plate. Incubate concomitant titer plate at 37° C. overnight.-   7. Load the dispenser with the remainder of the suspension and array    each labeled 1536-well plate at 4 uL per well. If the dispenser    leaves air bubbles in some wells, they can be removed by    centrifuging the plates at 200×g for 1 minute.-   8. Add 0.5 uL of positive control phage to well position AD46 of at    least two of the assay plates. Use a strong amylase-positive lambda    clone for this purpose.-   9. Incubate assay plates at 37° C. overnight in a humidified (≧95%)    incubator.

Day2

-   17. Count the pfu on the concomitant titer plate and determine the    average seed density per well (in pfu per well).-   18. Pintool at least 2 plates of each library screen (preferably the    2 containing positive controls) as follows:    -   a) Prepare 2 host lawn plates to act as a surface on which to        pintool: combine 250 uL of OD1 host cells with 2 mL 2% red        starch and plate with 9 mL top agar onto 150 mm NZY plates. Hold        each plate as level as possible as the top agar solidifies in        order to produce an even hue of red across the plate.    -   b) Using a twice flame-sterilized 1536 position pintool,        replicate at least 2 of the screening plates onto the host lawn        plates.    -   c) Place the pintooled recipient plates in a laminar flow hood        with the lids off for about 15-30 minutes (to vent off excess        moisture).    -   d) Replace the lids and incubate inverted at 37° C. overnight.

19. Prepare the 2× BODIPY starch substrate buffer as follows:

-   -   a) Calculate the total volume of 2× substrate buffer solution        needed for all screening plates at 4 uL per well (including any        extra deadspace volume required by the dispenser) and measure        this amount of 100 mM CAPS pH 10.4 into a vessel appropriate for        the dispenser used.    -   b) Retrieve enough 0.5 mg tubes of BODIPY starch to produce the        required volume of 2× substrate buffer [calculated in step a)        above] at a final concentration of 20-30 ug/mL.    -   c) Dissolve each 0.5 mg tube in 50 uL DMSO at room temperature,        protected from light, with frequent vortexing. This takes more        than 15 minutes; some production lots of BODIPY starch dissolve        better than others.    -   d) Add 50 uL 100 mM CAPS buffer pH 10.4 to each tube and mix by        vortexing.    -   e) Pool the contents of all tubes and remove any undissolved        aggregates by centrifuging for 1 minute at maximum speed in a        microfuge.    -   f) Add the supernatant to the rest of the 100 mM CAPS buffer        measured in step a) above.    -   g) Protect the 2× substrate buffer from light by wrapping in        foil.

-   20. Take plates and substrate buffer to the automation room and    program the robot with the following parameters:    -   a) dispense 4 uL substrate buffer per well    -   b) 1^(st) read at 1 hour post-substrate, 2^(nd) read at 9 hours,        and third read at 17 hours; with 37° C. incubation between reads    -   c) excitation filter: 485 nm; emission filter: 535 nm    -   d) set the Spectrafluor gain at 70.    -   e) ensure that the incubator used will protect assay plates from        light.

Day 3

1. Check pintooled plates for clearings in the bacterial lawn at allpositions corresponding to wells on the associated assay plate. Alsocheck for clearings in the red starch in any of the pin positions. Ifplates containing positive controls were used for pintooling, you shouldbe able to see a large clearing zone in the red background. Be wary ofcontaminants that also form clearing zones in red starch (see comment“Contaminants That Form Clearing Zones in Red Starch” at end of Example7).

2. Identify putative hits from the data file produced by the robotcomputer. The KANAL program produced by Engineering simplifies dataanalysis. As a rule of thumb, a putative hit is characterized as a wellhaving signal intensity rising at least 1.5 fold over background.

3. For each putative, remove 2 uL from the well and add to a tubecontaining 500 uL SM buffer and 50 uL CHCl3. Vortex to mix and store at4° C. This solution will be referred to hereafter as the 4e-3 stock. Theoriginal screening plates should be stored at 4° C., protected fromlight, at least until breakouts are complete.

This is the recommended method of breaking out putative hits. It is aliquid phase assay that relies on confirmation of activity on BODIPYstarch. Alternatively, putative hits can be plated directly onto solidphase plates containing red starch such that 2,000-3,000 pfu per hit areexamined for clearing zones. However, inability to observe clearingzones on red starch is not necessarily an indication that a putative hitwas a false positive. It would then need to be assayed using the formatin which it was originally identified (i.e., liquid phase using BODIPYstarch as substrate). In addition, very weak positives are more easilyidentified using the method detailed below.

Day 1

-   1. In a sterile 50 mL conical tube, combine 0.5 mL OD5 host cells    with 45.5 mL NZY. This will be referred to as the host-medium    suspension.-   2. For each putative hit to be analyzed, aliquot 1 mL of host-medium    suspension into each of 3 three sterile microfuge tubes.-   3. Set the 12-channel pipetman in multidispense mode with an aliquot    size of 20 uL and an aliquot number of 2×. Mount the pipetman with a    clean set of sterile tips.-   4. Pour about 1 mL of host-medium suspension into a new sterile    solution basin and load the multichannel pipetman.-   5. Dispense 20 uL per well into the last row (row P) of a black    384-well plate (12 channels×2=24 wells). This row will be used later    for the controls.-   6. Expel the remaining liquid in the tips by touching the tips    against the surface of the basin and pressing the RESET button on    the pipetman. Lay the pipetman down in a way to prevent    contamination of the tips. There is no need to change the tips at    this point.-   7. Pour the remainder of the fluid in the basin into a waste    container (like a beaker) taking care to avoid splash-back    contamination.-   8. For the first putative to be analyzed, take 111 uL of the 4e-3    stock (see Day 2 in Lambda Microtiter Screening for Amylases) and    add it to the first in a set of three tubes containing 1 mL    host-medium suspension (step 2). Vortex to mix. This is Dilution A.-   9. Take 111 uL of Dilution A and add to the next tube in the set.    Vortex to mix. This is Dilution B.-   10. Take 111 uL of Dilution B and add to the last tube in the set.    Vortex to mix. This is Dilution C. You should now have three    dilutions of phage, where concentrations of each differ by a factor    of 10.-   11. Pour the contents of Dilution C (the most dilute of the 3    samples) into the solution basin and load the multichannel pipetman.-   12. Dispense 20 uL per well into the first row of the 384-well plate    (12 channels×2=24 wells).-   13. Expel the remaining liquid in the tips by touching the tips    against the surface of the basin and pressing the RESET button on    the pipetman. Lay the pipetman down in a way to prevent    contamination of the tips. There is no need to change the tips at    this point.-   14. Empty the basin as described above.-   15. Pour the contents of Dilution B into the same basin and load the    multichannel pipetman.-   16. Dispense 20 uL per well into the second row of the 384-well    plate.-   17. Perform steps 13-16 similarly to dispense Dilution A into the    third row of the plate.-   18. After all three dilutions have been arrayed into the first 3    rows of the plate, discard all tips and the solution basin into the    biohazardous waste container.-   19. Mount the pipetman with a clean set of sterile tips and open a    new sterile solution basin.-   20. Repeat steps 8-19 for each remaining putative hit, using    remaining rows on the plate up to row O. Five putative hits can be    analyzed on one 384-well plate, with the last row (row P) saved for    the controls.-   21. Add 0.5 uL of each control to a separate well. Use at least 2-3    separate controls, preferably covering a range of activity.-   22. Incubate assay plates at 37° C. overnight in a humidified (≧95%)    incubator.

Day 2

-   1. Pintool all breakout plates onto a host lawn with red starch    using the same method described for Day 2 in Lambda Microtiter    Screening for Amylases, except that a 384 position pintool is used.-   2. Prepare the 2× BODIPY starch substrate buffer as follows:    -   a) Calculate the total volume of 2× substrate buffer solution        needed for all breakout plates at 20 uL per well (including any        extra deadspace volume required by the dispenser) and measure        this amount of 100 mM CAPS pH 10.4 into a vessel appropriate for        the dispenser used.    -   b) Retrieve enough 0.5 mg tubes of BODIPY starch to produce the        required volume of 2× substrate buffer [calculated in step a)        above] at a final concentration of 20-30 ug/mL.    -   c) Dissolve each 0.5 mg tube in 50 uL DMSO at room temperature,        protected from light, with frequent vortexing. This takes more        than 15 minutes; some production lots of BODIPY starch dissolve        better than others.    -   d) Add 50 uL 100 mM CAPS buffer pH 10.4 to each tube and mix by        vortexing.    -   e) Pool the contents of all tubes and remove any undissolved        aggregates by centrifuging for 1 minute at maximum speed in a        microfuge.    -   f) Add the supernatant to the rest of the 100 mM CAPS buffer        measured in step a) above.    -   g) Protect the 2× substrate buffer from light by wrapping in        foil.-   3. Dispense 20 uL per well into all breakout plates.-   4. Wrap all plates in aluminum foil and incubate at room temperature    for 2-6 hours.-   5. Read each plate in the Spectrafluor with the following settings:    -   a) fluorescence read (excitation filter: 485 nm; emission        filter: 535 nm)    -   b) plate definition: 384 well black    -   c) read from the top    -   d) optimal gain    -   e) number of flashes: 3-   6. On the resulting Excel spreadsheet, chart each putative's 3 rows    in a separate graph and check for activity. Ensure that the    positives controls produced signals over background.-   7. For each putative that appears to have a real signal among the    wells, harvest a sample from a positive well as follows:    -   a) Select a positive well from a row representing the highest        initial dilution.    -   b) Transfer 2 uL from that well into a tube containing 500 uL SM        and 50 uL CHCl₃. This is referred to as the breakout stock.    -   c) Store at 4° C.-   8. Using methods previously described, plate about 10 uL of each    breakout stock onto 150 mm NZY plates using red starch. The    objective is to obtain several (at least 20) well-separated plaques    from which to core isolates.

Day 3

-   1. Check pintooled plates for an acceptable incidence of clearings    in the bacterial lawn corresponding to wells on the associated assay    plate. Also check for clearings in the red starch in the positive    controls and in any tested putatives. Be wary of contaminants that    also form clearing zones in red starch (see below).-   2. From the solid phase plates containing dilutions of breakout    stocks, core several isolated plaques, each into 500 uL SM with 50    uL CHCl₃. This is referred to as the isolate stock.-   3. The isolate stocks can then be individually tested on BODIPY    starch using methods described above. This step can be skipped if    the plaque that was cored in step 2 produced a clearing zone in the    red starch background. The isolate stocks were then be individually    tested on BODIPY starch using methods described above. However, this    step may be skipped if the plaque that was cored in step 2 produced    a clearing zone in the red starch background.    Excisions

Day 1

-   1. In a Falcon 2059 tube, mix 200 uL OD1 XL1-Blue MRF' host, 100 uL    lambda isolate stock and 1 uL ExAssist phage stock.-   2. Incubate in 37° C. shaker for 15 minutes.-   3. Add 3 mL NZY medium.-   4. Incubate in 30° C. shaker overnight.

Day 2

-   1. Heat to excision tube to 70° C. for 20 minutes.-   2. Centrifuge 1000×g for 10 minutes.-   3. In a Falcon 2059 tube, combine 50 uL supernatant with 200 uL    EXP505 OD1 host.-   4. Incubate in 37° C. shaker for 15 minutes.-   5. Add 300 uL SOB medium.-   6. Incubate in 37 C. shaker for 30-45 minutes.-   7. Plate 50 uL on large LB_(Kan50) plate using sterile glass beads.    If the plates are “dry”, extra SOB medium can be added to help    disburse the cells.-   8. Incubate plate at 30° C. for at least 24 hours.-   9. Culture an isolate for sequencing and/or RFLP.-   Growth at 30° C. reduces plasmid copy number and is used to mitigate    the apparent toxicity of some amylase clones.    a. Contaminants that Form Clearing Zones in Red Starch

When using red starch on solid medium to assay phage for amylaseactivity, it is common to see contaminating colony forming units (cfu)that form clearing zones in the red starch. For pintooled plates, it isimportant to distinguish amylase-positive phage clones from thesecontaminants whenever they align with a particular well position. Thesource of the contaminating microbes is presumably the 2% red starchstock solution, which cannot be sterilized by autoclaving or byfiltering after preparation. It is thought that they are opportunisticorganisms that survive by metabolizing the red starch. In order toreduce these contaminants, use sterile technique when making 2% redstarch solutions and store the stocks either at 4° C. or on ice. Replacethe stocks every 1-2 weeks or whenever a high incidence of contaminantsis observed.

Example 5 Amylase Ligation Reassembly

Nine fragments (each about 150 bp) were amplified from each of theparent clones SEQ ID NO.: 6, SEQ ID NO.: 66, SEQ ID NO.: 67, coveringthe whole open reading frame. The primers are provided in Table 3.

TABLE 3 SEQ ID NO: GAACACTAGTAGGAGGTAACTTATGGCAAAGTATTCCGAGCTCGAAG 11SpeI GAACGGTCTCATTCCGCCAGCCAGCAAGGGGATGAGCGG 12 BsaIGAACCGTCTCAAAACACGGCCCATGCCTACGGC 13 BsmBIGAACGTCTCACCTCGACTTCCACCCCAACGAGGTCAAG 14 BsmAIGAACGTCTCAGGCGCTTTGACTACGTGAAGGGC 15 BsmAIGAACGGTCTCAACAAGATGGATGAGGCCTTTG 16 BsaIGAACCGTCTCACGATATAATCTGGAACAAGTACCTTGC 17 BsmBIGAACCGTCTCAGAAGCACGAGCATAGTTTACTACG 18 BsmBIGAACCGTCTCAAAGGTGGGTTTATGTGCCG 19 BsmBIGAACGTCTCAGGAATCCAAATGGCGGATATTCCCGC 20 BsmAIGAACGGTCTCAGTTTATCATATTGATGAGCTCC 21 BsaIGAACCGTCTCAGAGGTAGTTGGCAGTATATTTG 22 BsmBIGAACGTCTCACGCCAGGCATCAACGCCGATG 23 BsmAI GAACGTCTCATTGTAGTAGAGCGGGAAGTC24 BsmAI GAACGGTCTCAATCGGTGTCGTGGTTTGCTAC 25 BsaIGAACCGTCTCACTTCCACCTGCGAGGTGGTC 26 BsmBI GAACCGTCTCACCTTCCAACCTTGCTCGAGC27 BsmBI TCGAGACTGACTCTCACCCAACACCGCAATAGC 28GAACACTAGTAGGAGGTAACTTATGGCCAAGTACCTGGAGCTCGAAG 29 SpeI AGGGAACGGTCTCATTCCCCCGGCGAGCAAGGGC 30 BsaI GAACCGTCTCAAAACACCGCCCACGCCTACGG31 BsmBI GAACGTCTCACCTCGACTTCCACCCCAAC 32 BsmAIGAACGTCTCAGGCGCTTCGACTACGTCAAGG 33 BsmAIGAACGGTCTCAACAAGATGGACGCGGCCTTTGAC 34 BsaIGAACCGTCTCACGATATAATTTGGAACAAGTACCC 35 BsmBIGAACCGTCTCAGAAGCACCGACATAGTCTAC 36 BsmBI GAACCGTCTCAAAGGTGGGTCTACGTTCCG37 BsmBI GAACGTCTCAGGAATCCATATTGCGGAGATTCCGGC 38 BsmAIGAACGGTCTCAGTTTATCATGTTCACGAGCTC 39 BsaIGAACCGTCTCAGAGGTAGTTGGCCGTGTACTTG 40 BsmBIGAACGTCTCAGCCATGCGTCAACGCCGATG 41 BsmAI GAACGTCTCATTGTAGTAGAGCGGGAAGTCG42 BsmAI GAACGGTCTCAATCGGTGTCGTGGTTTGCAACG 43 BsaIGAACCGTCTCACTTCCACCGGCGAGGTGGTCGTG 44 BsmBIGAACCGTCTCACCTTCCGGCCTTGCTCGAGCC 45 BsmBITCGAGACTGACTCTCAGCCCACCCCGCAGTAGCTC 46GAACACTAGTAGGAGGTAACTTATGGCCAAGTACTCCGAGCTGGAAG 47 SpeI AGGGAACGGTCTCATTCCTCCCGCGAGCAAGGG 48 BsaI GAACCGTCTCAAAACACCGCCCACGCCTATG49 BsmBI GAACGTCTCACCTCGACTTCCACCCGAACGAGC 50 BsmAIGAACGTCTCAGGCGCTTCGACTACGTCAAGG 51 BsmAIGAACGGTCTCAACAAGATGGACGAGGCCTTCG 52 BsaI GAACCGTCTCACGATATAATCTGGAACAAG53 BsmBI GAACCGTCTCAGAAGCACTGACATCGTTTACTACG 54 BsmBIGAACCGTCTCAAAGGTGGGTTTACGTTCCG 55 BsmBI GAACGTCTCAGGAATCCATATCGCCGAAAT56 BsmAI GAACGGTCTCAGTTTATCATGTTTATGAGC 57 BsaIGAACCGTCTCAGAGGTAGTTGGCCGTGTATTTAC 58 BsmBIGAACGTCTCACGCCAGGCATCGATGCCGAT 59 BsmAIGAACGTCTCATTGTAGTAGAGGGCGAAGTCAAAG 60 BsmAIGAACGGTCTCAATCGGTATCGTGGTTGGCTACAAAC 61 BsaIGAACCGTCTCACTTCCTCCGGCGAGGTTGTCATG 62 BsmBIGAACCGTCTCACCTTCCGGCTTTGCTTGAGGC 63 BsmBITCGAGACTGACTCTCACCCAACACCGCAGTAGCTCC 64CACACAGCAGCAACCAACCTCGAGACTGACTCTCASCC 65 BbvI

Conditions used for PCR were as follows: 3 min 94° C., (30 sec 94° C.;30 sec 55° C., 30 sec 68° C.)×30 cycles, followed by 10 min 68° C. PCRproducts corresponding to homologous regions from the three parents werepooled (1:1:1), cut with the appropriate restriction enzyme (see Table3), and gel-purified. Equal amounts of fragment pools were combined andligated (16° C.; over night). The resulting 450 bp ligation productswere gel purified and ligated to yield full length amylase genes. Theresulting full length products were gel-purified and PCR amplified usinga mixture of F1 primers SEQ ID NO.: 6, SEQ ID NO.: 66, SEQ ID NO.: 67and primer SEQ ID NO:65. Conditions used for PCR were as follows: 3 min94° C., (30 sec 94° C.; 30 sec 50° C., 60 sec 68° C.)×30 cycles,followed by 10 min 68° C. The resulting PCR products (˜1.4 kbp) werepurified, cut with SpeI and BbvI, gel-purified, ligated into pMYC(vector from Mycogen, cut with SpeI/XhoI), and transformed into E. coliTop 10. Plasmid DNA from a pool of ˜21000 colonies was isolated andtransformed into Pseudomonas.

Screening of Reassembled α-Amylase

The transformed Pseudomonas fluorescens (MB214) containing pMYC derivedfrom the parent clones SEQ ID NO:6, SEQ ID NO:66, SEQ ID NO:68 weresorted to 96- or 384-well plates by FACS and treated with 6M urea.Primary screening using RBB-starch and/or FITC-starch as substrates wascarried out as described more fully below. Elevated active clones werescreened using RBB-starch as substrate using induced cultures and byliquefaction assay. Stock and sequencing new elevated active clonesbased on liquefaction data was performed.

The transformed reassembled amylase library (MB214 (Pf)), were collectedand sorted into 96-well plates (or 384-well plates) at 1 cell/well in 50μl of LB+Tet. The plates were incubated for 24 hours at 30° C. Replicateplates were made corresponding to each well for storage. Forty-five (45)μl of 12M urea was added to each well and the plates were shaken for 10minutes. Plates were kept at room temp for at least 1 hour and thelysate stored at 4° C.

Assay Using RBB-Starch

75 μl of RBB-starch substrate (1% RBB-insoluble corn starch in 50 mMNaAc buffer, pH=4.5) was added into each well of a new 96-well plate(V-bottom). Five micro-liters of enzyme lysate was transfered into eachwell with substrate using Biomek or Zymark. The plates were sealed withaluminum sealing tape and shaken briefly on the shaker. The plates wereincubated at 90° C. for 30 minutes, followed by cooling at roomtemperature for about 5 to 10 minutes. One hundred micro-liters of 100%ethanol was added to each well, the plates sealed and shaken briefly onthe shaker. The plates were then centrifuged 400 rpm for 20 minutesusing bench-top centrifuge. 100 μl of the supernatant was transferredinto a new 96-well plate (flat bottom) by Biomek and read OD₅₉₅.Controls: SEQ ID NO:6, SEQ ID NO:66, SEQ ID NO:68.

Assay Using FITC-Starch

Added 50 μl of substrate (0.01% FITC-starch in 100 mM NaAc buffer,pH=4.5) into each well of a new 384-well plate. Transfered 5 μl ofenzyme lysate into each well with substrate and incubated the plate atroom temperature overnight. The polarization change of the substrate,excitation 485 nm, emission 535 nm, was read for each well. Controls:SEQ ID NO:6, SEQ ID NO:66, SEQ ID NO:68. Preferably 96 well plates areused for all assays.

Confirmation of New Active Clones

Each positive clone from screening was grown and induced using astandard protocol. Each clone was examined for growth (i.e., celldensity over time), activity at per cell level (RBB-starch assay andliquefaction assay), expression (protein gel) and solubility of protein(by microscope analysis). The confirmed new elevated clones weretransferred for fermentation. One of the clones have amylase activitygreater than that of the parent includes the enzyme set forth in SEQ IDNO:2 (encoded by SEQ ID NO:1).

Example 6 Amylase Liquefaction

This example characterizes the liquefaction oligosaccharide patternsresulting from the invention enzymes, SEQ ID NO:6 and SEQ ID NO:2 vscommercial Bacillus licheniformis and Bacillus stearothermophilusamylases. These results looked at the saccharification progress andfinal dextrose levels from syrups generated by invention and commercialamylases.

Three commercial enzymes, Genencor Spezyme AA, and two others allrequired more than double the recommended dosage to achieve the targetDextrose equivalent (DE). Dextrose equivalent (DE) is the industrystandard for measuring the concentration of total reducing sugars,calculated as D-glucose on a dry weight basis. Unhydrolyzed granularstarch has a DE of virtually zero, whereas the DE of D-glucose isdefined as 100.

This confirms the “double dosage” effect for all Bacillus amylases andgives more credence to the proposal that the observed dosage for SEQ IDNO:2 in the trials is also twice the value which would be required undermore normal conditions. The projected “normal” dosage, 60-70 Units/kilostarch at pH 4.5 to reach a 19 DE, is consistent with the laboratoryliquefaction data.

The oligosaccharide pattern generated by invention amylases is differentfrom the Bacillus profiles. The molecular weight distribution for theBacillus amylases (gel permeation chromatography with detection by lightscattering and viscosity) is bimodal with a substantial fraction at thevery high molecular weight range (>300,000) even at an 18 DE. The SEQ IDNO:2 at 18 DE exhibits a uniform distribution with nothing greater than20,000. This is consistent with the lower viscosity for Inventionsyrups. The DP (degrees of polymerization) profiles as measured by HPLCalso reflects this difference in action pattern.

In this study, as well as in the previous studies, the final glucoselevel after saccharification of Invention amylase liquefied syrups vsthe Bacillus syrups is the same for both cases. However, we have nowacquired sufficient saccharification data from internal as well as fromthe GPC studies to confirm that the non-dextrose residuals for theinvention amylases are different from the Bacillus amylase syrups.Although the dextrose and maltose levels are essentially the same forboth, the Invention amylases have a higher DP3 fraction but lower amountof the “highers” vs. the Bacillus enzyme. Consistent with the absence ofhigh molecular weight fragments after liquefaction, the postsaccharification Invention syrups have a lower content of the >DP7fraction.

Glucose DP2 DP3 >DP7 SEQ ID NO: 2 95.25 2.39 1.13 0.91 Commercial 94.162.10 0.39 2.91 SEQ ID NO: 6 94.77 2.27 1.48 0.82

SEQ ID NO:2 amylase concentrate was prepared from fermentation broths byheat treatment, cell washing, alkaline extraction using microfiltrationand ultraflitration (48% overall yield). The UF concentrate wasneutralized with acetic acid and formulated with 30% glycerol at pH 4.5.The activity level of the slurry formulation was representative of acommercial product (120 U¹/g−0.5 kg/ton starch).

Standard Amylase Activity Assay

A 1 mL cuvette containing 950 μL of 50 mM MOPS pH 7.0 containing 5 mMPNP-α-D-hexa-(1→4)-glucopyranoside was placed in the Peltier temperaturecontroller of the Beckman DU-7400 spectrophotometer preheated to 80° C.The spectrophotometer was blanked at 405 nm and 50 μL of the enzymesolution was added to the cuvette, mixed well and the increase in theOD405 nm was monitored over a one-minute interval. The ΔOD_(405 nm/min)rate is converted to a standard unit of μmole/minute from theOD_(405 nm) response of 50 μL of 1 μmole/mL PNP in 950 mL 50 mM MOPS atpH 7.0-80° C. One standard Diversa unit of thermostable alpha amylase(DTAA) is equal to the amount of enzyme that will catalyze the releaseof 1 μmole/mL/minute of pNP under the defined conditions of the assay.

Standard Glucoamylase Activity Assay

A 1 mL cuvette containing 950 μL of 50 mM MOPS pH 7.0 containing 5 mMpNP-α-D-glucopyranoside was placed in the Peltier temperature controllerof the Beckman DU-7400 spectrophotometer preheated to 60° C. Thespectrophotometer was blanked at 405 nm and 50 μL of the enzyme solutionwas added to the cuvette, mixed well and the increase in the OD_(405 nm)was monitored over a one-minute interval. The ΔOD_(405 nm)/min rate isconverted to a standard unit of pmole/minute from the OD_(405 nm)response of 50 μL of 1 μmole/mL pNP in 950 mL 50 mM MOPS at pH 7.0-60°C. One standard Diversa unit of glucoamylase (DGA) is equal to theamount of enzyme that will catalyze the release of 1 μmole/mL/minute ofpNP under the defined conditions of the assay.

Dextrose Equivalent Determination

The neocuproine method was used to measure the DE. Selected samples weremeasured by both the Invention procedure and by a GPC analyst using theGPC Fehlings procedure.

Neocuproine Assay

A 100 μl sample was added to 2.0 ml of neocuproine solution A (40 g/Lsodium carbonate, 16 g/L glycine, 0.45 g/L copper sulfate). To this wasadded 2.0 ml of neocuproine solution B (1.2 g/L neocuproinehydrochloride-Sigma N-1626). The tubes were mixed and heated in aboiling water bath for 12 minutes; cooled, diluted to 10 ml volume withDI water and the OD read at 450 nm on the spectrophotometer. The glucoseequivalent in the sample was extrapolated from the response of a 0.2mg/ml glucose standard run simultaneously.

The starch sample is diluted ˜1 to 16 with DI water with the exactdilution recorded. Ten milliliters of the diluted sample was added to 20mls of DI water. Ten milliliters of Fehlings solution A and B were addedto the diluted starch. The sample was boiled for 3 minutes and cooled onice. Ten milliliters of 30% KI and 10 ml of 6N H₂SO₄ was added. Thesolution was titrated against 0.1N sodium thiosulfate. The titrantvolume is recorded and used to calculate the DE.Residual Starch DeterminationPost-saccharification samples were checked for residual starch using theStaley iodine procedure

Twenty grams of sample was weighed into a large weigh dish. 45 μL ofIodine solution is added to the weigh dish and the starch solution ismixed well. Dark blue indicates the presence of starch, a lightblue-green indicates slight starch, light green indicates a trace ofstarch and yellow-red, absence of starch. Iodine solution is prepared bydissolving 21.25 grams of iodine and 40.0 grams of potassium iodide inone liter of water.

Oligosaccharide Profile

Liquefaction and saccharification carbohydrate profiles were measured byHPLC (Bio-Rad Aminex HPX-87C column in calcium form −80 C.) usingrefractive index detection.

Gel Permeation Chromatography

The molecular weight distribution was determined by chromatography on aPL Aquagel-OH column with mass detection by refractive index (WatersModel 2410). A Viscotek Model T60 detector was used for continuousviscosity and light scattering measurements.

Capillary Electrophoresis

Beckman Coulter P/ACE MDQ Glycoprotein System—separation of APTSderivatized oligosaccharides on a fused silica capillary—detection bylaser-induced fluorescence.

Primary Liquefaction

Line starch directly from the GPC process is pumped into a 60 liter feedtank where pH, DS (dry solids) and calcium level can be adjusted beforeliquefaction. The amylase is added to the slurry. The 32% DS slurry ispumped at 0.7 liter/minute by a positive displacement pump to the jet—apressurized mixing chamber where the starch slurry is instantaneouslyheated to greater than 100 C. by steam injection. The gelatinizedpartially liquefied starch is pumped through a network of piping (stillunder pressure) to give the desired dwell time (5 minutes) attemperature. The pressure is released into a flash tank and samples canbe taken. Samples were taken in duplicate.

Secondary Liquefaction

The liquefied starch was collected in one liter glass bottles and heldin a water bath at 95 C. for 90 minutes.

Saccharification

Liquefied starch was cooled to 60 C., the pH adjusted to 4.5 and thesamples treated with glucoamylase. Saccharification progress wasmonitored over time by HPLC.

Preparation of Liquefied Syrups for Analysis

These trials were run to obtain liquefied syrups at DE's of 12 and 18for three amylases; SEQ ID NO:6, SEQ ID NO:2, commercial B.licheniformis amylase. The syrups were saccharified with three levels ofglucoamylase. The liquefied syrups were also analyzed by HPLC and gelpermeation chromatography.

Saccharification

The liquefied syrups produced with each amylase were adjusted toapproximately pH 2.5 with 6N HCl immediately after the 90 minutesecondary liquefaction to inactivate any residual amylase. The syrupswere then adjusted to pH 4.5, placed in a 60 C. water bath andsaccharified with three levels of glucoamylase. The extent ofsaccharification was monitored by HPLC at 18-88 hour time points.

The liquefied syrups were saccharified with the standard dosage—0.04% ofa double-strength glucoamylase—and two lower dosages (50% and 25%) tomonitor any differences in the saccharification progress. As theprevious plots and the tables below indicate, the glucose levels arehigher at earlier time points with the SEQ ID NO:2 syrups. Some of thedifference is due to a higher starting point but the molecular weightprofile difference is also a contributing factor (the oligosaccharidesin the SEQ ID NO:2 liquefied syrups—being smaller and moreuniform—should be, and apparently are, better substrates forglucoamylase).

Saccharification Progress-% dextrose development vs time-0.04%glucoamylase Amylase 18 hr 24 hr 40 hr 44 hr 88 hr Commercial 70.2 78.486.1 86.7 94.2 SEQ ID NO: 2 79 88.6 92.5 92.8 95.3 SEQ ID NO: 6 74.185.9 91.9 91.6 94.8 Saccharification Progress-% dextrose development vstime-0.02% glucoamylase Amylase 18 hr 24 hr 40 hr 44 hr 88 hr B.licheniformis 54.5 66.7 76.1 77.2 90.9 Amylase SEQ ID NO: 2 60.1 72 84.885.3 93.6 SEQ ID NO: 6 57.1 70 84 86.5 92.5Post-Saccharification Sugar Profile

In these studies and all previous saccharification studies, the finalglucose level achieved after saccharification of Invention amylase andB. licheniformis liquefied syrups is essentially identical. The DP2(maltose) level is also similar. These large fragments are poorsubstrates for glucoamylase and tend to be converted slowly, if at all,into smaller fragments and ultimately, glucose).

′DP Glucose 2 DP3 >DP7 SEQ ID NO: 2 95.25 2.39 1.13 0.91 Commercial94.16 2.10 0.39 2.91 SEQ ID NO: 6 94.77 2.27 1.48 0.82

Molecular Weight Distribution

The molecular weight distribution of syrups liquefied to DE's of 12 and18 by Invention amylases (SEQ ID NO:6 and SEQ ID NO:2) and commercialBacillus licheniformis and commercial Bacillus stearothermophilus) weremeasured by gel permeation chromatography using detection by refractiveindex, light scattering and viscosity. Both the licheniformis andstearothermophilus amylases generate a bimodal distribution—the primarypeak centered at 2000, a secondary peak at 32,000 with a shoulderextending past the 160,000 range. The lower molecular weight peakrepresents approximately 60% of the total mass of the sample. TheInvention amylases exhibit a single peak at 2000 with very little above30,000.

HPLC

The DE 12 and 18 syrups produced by the Invention and commercialamylases were analyzed by HPLC. Both techniques(chromatograms/electropherograms shown in Appendices) producefingerprints characteristic of each class of amylase; theoligosaccharide patterns are different for licheniformis vsstearothermophilus vs the Invention amylases. The Invention liquefiedsyrups exhibit evidence of greater branching in the oligosaccharides.HPLC only resolve the oligosaccharides in the <DP15 range—largerfragments are not visible in these techniques. Bacillus amylases areknown to liquefy starch in a manner such that the amylopectin fractionis hydrolyzed less extensively than the amylose fraction. These >DP30amylopectin fragments are contained in the high molecular weightfraction centered at 32,000 and consequently, little evidence ofbranching is seen in the HPLC analyses of the Bacillus liquefied syrups.The <DP15 oligosaccharides from Invention amylases contain fragmentsfrom both amylose and amylopectin.

Although the invention has been described with reference to thepresently preferred embodiment, it should be understood that variousmodifications can be made without departing from the spirit of theinvention. Accordingly, the invention is limited only by the followingclaims.

1. An isolated, synthetic or recombinant nucleic acid comprising (a) asequence having at least or about 95% sequence identity to SEQ ID NO:1,wherein the nucleic acid encodes a polypeptide having alpha amylaseactivity; and (b) sequences fully complementary to (a).
 2. An isolated,synthetic or recombinant nucleic acid comprising (a) a sequence encodinga polypeptide having alpha amylase activity, wherein the complement ofsaid sequence hybridizes under highly stringent conditions to SEQ IDNO:1, and (b) sequences fully complementary to (a), wherein the highlystringent conditions comprise a hybridization under conditionscomprising a buffer comprising 50% formamide at about 37° C. to 42° C.;or, 42° C. in 50% formamide, 5× SSPE, 0.3% SDS, and a wash stepcomprising use of a buffer comprising 0.15 NaCl for 15 min at 72° C. 3.The isolated, synthetic or recombinant nucleic acid of claim 1, whereinsaid sequence has at least about 97% sequence identity to SEQ ID NO:1.4. The isolated, synthetic or recombinant nucleic acid of claim 3,wherein said sequence has at least about 98% sequence identity to SEQ IDNO:1.
 5. The isolated, synthetic or recombinant nucleic acid of claim 1,wherein the sequence identity is determined using a sequence comparisonalgorithm comprising FASTA version 3.0t78 with the default parameters.6. An isolated, synthetic or recombinant nucleic acid encoding apolypeptide having an amino acid sequence having at least about 95%sequence identity to SEQ ID NO:2, wherein the polypeptide is capable ofhydrolyzing a starch to a sugar.
 7. A method of producing a recombinantpolypeptide comprising the steps of introducing a nucleic acid encodingthe polypeptide into an isolated host cell under conditions that allowexpression of the polypeptide, wherein the nucleic acid comprises thesequence of claim
 1. 8. A method of producing and recovering arecombinant polypeptide comprising the steps of: introducing the nucleicacid of claim 1 operably linked to a promoter, into an isolated hostcell under conditions that allow expression of the polypeptide, andrecovering the recombinant polypeptide.
 9. A method of generating anamylase-encoding polynucleotide comprising: obtaining theamylase-encoding nucleic acid of claim 1 or claim 2 and modifying one ormore nucleotides in said polynucleotide to another nucleotide, deletingone or more nucleotides in said polynucleotide, or adding one or morenucleotides to said polynucleotide to obtain a modified nucleic acidsequence, wherein the modified nucleic acid sequence encodes anpolypeptide having an amylase activity.
 10. The method of claim 9,wherein the modifications are introduced by a method selected from thegroup consisting of: effor-prone PCR, shuffling,oligonucleotide-directed mutagenesis, assembly PCR, sexual PCRmutagenesis, in vivo mutagenesis, cassette mutagenesis, recursiveensemble mutagenesis, exponential ensemble mutagenesis, site-specificmutagenesis, gene reassembly, Gene Site Saturation Mutagenesis (GSSM)and any combination of these methods.
 11. The method of claim 10,wherein the modifications are introduced by effor-prone PCR.
 12. Themethod of claim 10, wherein the modifications are introduced byshuffling.
 13. The method of claim 10, wherein the modifications areintroduced by oligonucleotide-directed mutagenesis.
 14. The method ofclaim 10, wherein the modifications are introduced by assembly PCR. 15.The method of claim 10, wherein the modifications are introduced bysexual PCR mutagenesis.
 16. The method of claim 10, wherein themodifications are introduced by in vivo mutagenesis.
 17. The method ofclaim 10, wherein the modifications are introduced by cassettemutagenesis.
 18. The method of claim 10, wherein the modifications areintroduced by recursive ensemble mutagenesis.
 19. The method of claim10, wherein the modifications are introduced by exponential ensemblemutagenesis.
 20. The method of claim 10, wherein the modifications areintroduced by site-specific mutagenesis.
 21. The method of claim 10,wherein the modifications are introduced by gene reassembly.
 22. Themethod of claim 10, wherein the modifications are introduced by GeneSite Saturation Mutagenesis (GSSM).
 23. A method for comparing a firstsequence to a second sequence comprising the steps of: reading the firstsequence and the second sequence through use of a computer program whichcompares sequences; and determining differences between the firstsequence and the second sequence with the computer program, wherein saidfirst sequence comprises the nucleic acid sequence of claim 1 or claim2.
 24. The method of claim 23, wherein the step of determiningdifferences between the first sequence and the second sequence furthercomprises the step of identifying polymorphisms.
 25. A method foridentifying a feature in a sequence comprising the steps of: reading thesequence using a computer program which identifies one or more featuresin a sequence; and identifying one or more features in the sequence withthe computer program, wherein the sequence comprises the nucleic acidsequence of claim 1 or claim
 2. 26. A nucleic acid probe for identifyingor isolating an amylase-encoding nucleic acid, comprising a nucleic acidthat specifically hybridizes under highly stringent hybridizationconditions to the amylase-encoding nucleic acid of claim 1 or claim 2,or its fully complementary sequence, wherein the highly stringenthybridization conditions comprise a hybridization under conditionscomprising 50% formamide at about 37° C. to 42° C.; or, 42° C. in 50%formamide, 5× SSPE, 0.3% SDS, and a wash step comprising use of a buffercomprising 0.15 NaCl for 15 min at 72° C.
 27. The probe of claim 26,wherein the nucleic acid comprises DNA or RNA.
 28. The probe of claim26, wherein the probe further comprises a detectable isotopic label or adetectable non-isotopic label.
 29. The probe of claim 28, wherein theprobe further comprises a detectable non-isotopic label selected fromthe group consisting of a fluorescent molecule, a chemiluminescentmolecule, an enzyme, a cofactor, an enzyme substrate, and a hapten. 30.A cloning vector comprising the nucleic acid of claim 1 or claim
 2. 31.An isolated host cell transformed or transfected with the nucleic acidof claim 1 or claim
 2. 32. An expression vector capable of replicatingin a host cell comprising the nucleic acid of claim 1 or claim
 2. 33. Acloning vector as claimed in claim 30, wherein the cloning vectorcomprises a viral vector, a plasmid, a phage, a phagemid, a cosmids, afosmid, a bacteriophage, an artificial chromosome, an adenovirus vector,a retroviral vector, or an adeno-associated viral vector.
 34. Anisolated host cell transformed or transfected with the expression vectorof claim
 32. 35. An isolated host cell as claimed in claim 31, whereinthe host is selected from the group consisting of prokaryotes,eukaryotes, funguses, yeasts, plants and non-human metabolically richhosts.
 36. A method of producing a recombinant polypeptide comprisingthe steps of (a) introducing a nucleic acid encoding the polypeptideinto an isolated host cell under conditions that allow expression of thepolypeptide, wherein the nucleic acid comprises the sequence of claim 2,or, (b) introducing the nucleic acid of claim 2 into an isolated hostcell under conditions that allow expression of the polypeptide, therebyproducing a recombinant polypeptide.
 37. An expression vector comprisingthe nucleic acid of claim 1 or claim 2, wherein the expression vectorcomprises a viral vector, a plasmid, a phage, a phagemid, a cosmids, afosmid, a bacteriophage, an artificial chromosome, an adenovirus vector,a retroviral vector, or an adeno-associated viral vector.
 38. Anisolated host cell transformed the nucleic acid of claim 1 or claim 2,wherein the cell is a prokaryote cell, a eukaryote cell, a fungus cell,a yeast cell, a plant cell or a non-human metabolically rich host cell.